EPISODE: 027 - APPROVED DOCUMENT L - CONSERVATION OF FUEL AND POWER - VOLUME 1 - DWELLINGS

BYTNAR - TALKS

EPISODE 027 - APPROVED DOCUMENT L - CONSERVATION OF FUEL AND POWER - VOLUME 1 - DWELLINGS

This episode is for people who want to know more about Approved Document Part L – Conservation of Fuel and Power – Volume 1 – Dwellings.

You should like this episode if you ask yourself questions like:

• How do I calculate the Total Energy Performance of a new dwelling using the Standard Assessment Procedure (SAP)?

• What are the target primary energy rates and fabric energy efficiency requirements for new dwellings under Approved Document L?

• What is the BREL report, and how is it used to compare actual and target energy performance metrics for buildings?

• What are the feasibility analysis requirements for implementing high-efficiency alternative systems like renewable energy before construction?

• What are the U-value standards for insulation in new and renovated dwellings, and how do they prevent thermal bridging?

• What efficiency standards must new and replaced building services meet to comply with energy conservation regulations?

• How is pressure testing conducted for new dwellings, and what are the air leakage regulations that need to be met?

• What steps are involved in the commissioning of fixed building services and on-site electricity generation systems to ensure energy efficiency?

• What documentation, such as the BREL report and energy performance certificate, must be provided to building owners upon completion of new or renovated dwellings?

LET'S TALK ABOUT YOUR PROJECT

---

This is Bytnar Talks: The Engineer Takes on Construction, Episode 27.

Hi, I'm Piotr Bytnar. Each day I help my clients plan and design building projects through Bytnar Limited, a consulting Chartered Structural Engineers practice.My biggest passion — and the cornerstone on which I've built my business — is finding clever solutions for construction projects.

I am a Chartered Structural Engineer and a budding software developer, so you can rest assured that I will strive to talk about best practices and the use of new technologies in the industry. And if you're embarking on a construction project, or are involved in planning, designing, and building the world around us, you'll find this podcast useful.

Approved Document L: Conservation of Fuel and Power, Volume One – Dwellings

Hi, and welcome to Bytnar Talks, your favorite podcast on all matters of architecture, engineering, and construction.It is Thursday, the 22nd of August, 2024, and I'm here back with you with the 27th episode and information on Approved Document L: Conservation of Fuel and Power, Volume One – Dwellings.

I think the weather is more patchy this year than my delivery of this podcast. At least you can tell it will be released once a week — well, usually. But with what is happening outside the window, you damn sure cannot.

Anyway, when the weather turns cool, I'm all the more happy to sit behind the microphone and deliver new content for you — especially this one that is rather long. That’s why it is delivered a fortnight after the last one.

Once I got to this, I just could not stop and make it in parts, as I did with Approved Document B.

However, before I go on to covering the material of this episode, let's have a look at what was covered last week.

In the last episode, I talked about the Approved Document K: Protection from Falling, Collision, and Impact. There are six requirements covered in this document, contained within 10 sections. These sections are as follows:

• Section 1 deals with stairs and landings, where minimum safety standards dictate the design of stairs — concentrating on consistent step geometry, proper riser dimensions, and secure handrails. Different requirements apply to private homes, public areas, and industrial buildings.

• Section 2, which deals with ramps and landings, tells us that ramps must meet specific gradient and width criteria, with mandatory landings and protective barriers to ensure accessibility and safety — especially in non-residential settings.

• Section 3 treats on protection from falling, where we are told that guard rails are required in areas with fall risks — like stairs and balconies — with specified height and strength standards. Additional safety measures may apply to maintenance areas.

• Section 4 emphasizes vehicle barriers and loading bays. These should be strong enough to mitigate vehicle collisions, and loading bays should have safety exit points or refuges to protect workers from impact from delivery lorries.

• Section 5 deals with glazing safety, where standards focus on impact resistance and the safe use of different glass types. Protective barriers may be necessary to prevent injuries.

• Section 6 treats on collision with open windows — especially in non-residential buildings — where barriers or other methods to prevent people from colliding with open windows need to be put in place.

• Section 7, Glazing Manifestation, tells us that large transparent glass in public spaces must be clearly marked at specified heights to prevent accidental collisions — you know, those little greyish or semi-transparent dots, stripes, or whatnot.

• Section 8, Safe Operation of Windows, simply tells us that windows in non-dwellings must have reachable controls and protective measures to safely operate them and prevent falls through open windows.

• Section 9, Access for Window Cleaning in Non-Residential Settings, must ensure safe access for window cleaning — including limits on reach and provisions for safe ladder use.

• Section 10, Indoor Safety, doors especially in residential buildings, must include safety features like vision panels and mechanisms to prevent injury from sliding, swinging, or falling doors — or even falling off a chair.

In this episode, I will move to Approved Document L: Conservation of Fuel and Power, Volume One – Dwellings.

So, without further ado, let's dive straight into this.

[Music]

In this episode, I will talk about the statutory guidance contained within Approved Document L: Conservation of Fuel and Power, Part One or Volume One – Dwellings.

Requirement LRequirements L are short and sweet — only two — but that is further expanded by 19 different additional regulations, including Regulation 6.Some regulations from Part 6 of the Building Regulations are included, as well as from Part 8 and Part 9.

There will be plenty of talk in this episode, so buckle up — because CANAS is going bye-bye!

The episode will follow the structure of the approved document from Section 0 to Section 12, and all the additional regulations along the way, as laid down in the document.

So, let's get into the nitty-gritty of this approved document.

Starting with the text of the legislation:

Part L – Conservation of Fuel and Power

Requirement L1 – Conservation of Fuel and PowerReasonable provision shall be made for the conservation of fuel and power in buildings by:A.Limiting heat gains and losses(i) through thermal elements and other parts of the building fabric, and(ii) from pipes, ducts, and vessels used for space heating, space cooling, and hot water services.

B.Providing fixed building services which—(i) are generally efficient to a reasonable standard,(ii) have effective controls, and(iii) are commissioned by testing and adjusting as necessary to ensure they use no more fuel and power than is reasonable in the circumstances.

Requirement L2 – On-site Generation of ElectricityWhere a system for on-site electricity generation is installed:A.

Reasonable provision must be made to ensure that:(i) the system and its electrical output are appropriately sized for the site and available infrastructure,(ii) the system has effective controls, and

B.It must be commissioned by testing and adjusting as necessary to ensure that it produces the maximum electricity that is reasonable in the circumstances.

Okay, so these are the paragraphs of the legislation requirements contained within Schedule 1. There will be more regulations popping in as we go along, so let's take it slow and methodically, as laid down in the approved document.

Section 0 gives us a little bit of an introduction to the whole lot. You already know that today we talk about dwellings, and there will be a second part coming, dealing with buildings other than dwellings.

We are reminded that dwellings are considered to be self-contained units. And if this includes flats, we are told that for common areas — like heated corridors — we need to consider appropriate measures as for the dwelling itself. But for unheated spaces, the fabric elements need to meet minimum standards.

Sections 1 to 9 deal with new dwellings.Conservatories in such new dwellings are considered separate if they are not heated and are thermally separated from the house. If not, it will need to be considered as part of the dwelling — necessitating primary energy rate, emission rate, and fabric efficiency rate calculations, as is the case for house.

Extensions and work on existing dwellings will follow the consideration of heat gain and losses from Section 4, building services considerations in Sections 5 and 6, and new or improved thermal elements in Sections 10, 11, and 12.

As ever, listed and historical buildings will be treated ever so slightly differently. If we can upgrade a thermal element, we ought to — but it is recognized that it is not prudent to force it on all such buildings.

Conservatory and porch-type extensions are also exempt under Regulation 21 if:

• the extension is at ground level,

• under 30 m²,

• the glazing complies with requirements K,

• it is divided from the building with an appropriate wall, door, or window, and

• the heating system of the house is not extended into that space.

Carports and otherwise covered areas are exempt from the regulation if under 30 m².

The workspace within a dwelling should be treated as a dwelling if the commercial use can be reverted into a dwelling.

The Approved Document L will have some interactions with other documents like Parts C, E, F, J, K, and M.

Now, a very important part of the whole consideration is the energy performance calculations for the dwellings. These are contained in Regulations 24, 25, 25B, 26, 26A, 26C, 27, 27A, as well as 27C.

I will now go on to read you the text of them all so you can return back to it whenever you want.

Methodology of Calculation of the Energy Performance – Regulation 24

(1) The Secretary of State shall approve:A.(a) a methodology for calculation of the energy performance of buildings, including methods for calculating asset ratings and operational ratings of buildings; andB.(b) ways in which the energy performance of buildings, as calculated in accordance with the methodology, shall be expressed.

(2) In this regulation:

• Asset rating means an energy performance indicator determined from the amount of energy estimated to meet the different needs associated with a standardized use of the building.

• Operational rating means an energy performance indicator determined from the amount of energy consumed during the occupation of a building over a period of time and the energy demand associated with a typical use of the building over that period.

Regulation 25 – Minimum Energy Performance Requirements for New DwellingsMinimum energy performance requirements shall be approved by the Secretary of State, calculated and expressed in accordance with the methodology approved pursuant to Regulation 24 for:

A. New buildings, which shall include new dwellings, in the form of Target CO₂ Emission Rates.B. New dwellings, in the form of Target Fabric Efficiency Rates.C. New buildings, in the form of Target Primary Energy Rates.

Regulation 25B – Nearly Zero Energy Requirements for New BuildingsWhere a building is erected, it must be a nearly Zero Energy Building.

Regulation 26 – CO₂ Emission Rates for New BuildingsWhere a building is erected, it shall not exceed the Target CO₂ Emission Rate for that building that has been approved pursuant to Regulation 25, applying the methodology of calculation and expression of the energy performance of buildings approved pursuant to Regulation 24.

Regulation 26A – Fabric Energy Efficiency Rate for New DwellingsWhere a dwelling is erected, it shall not exceed the Target Fabric Energy Efficiency Rate for the dwelling that has been approved pursuant to Regulation 25, applying the methodology of calculation and expression of the energy performance of buildings approved pursuant to Regulation 24.

Regulation 26C – Target Primary Energy Rates for New BuildingsWhere a building is erected, it must not exceed the Target Primary Energy Rate for the building, which has been approved pursuant to Regulation 25C, applying the methodology of calculation and expression of the energy performance of buildings approved pursuant to Regulation 24.

Regulation 27 – CO₂ Emission Rate Calculations

(1) This regulation applies where a building is erected and Regulation 26 applies.

(2) Not later than the day before the work starts, the person carrying out the work shall give the local authority a notice which specifies:A. The Target CO₂ Emission Rate for the building, calculated and expressed in accordance with the methodology approved pursuant to Regulation 24.B. The CO₂ Emission Rate for the building as designed, calculated and expressed in accordance with the methodology approved pursuant to Regulation 24.C. A list of specifications to which the building is to be constructed.

(3) Not later than 5 days after the work has been completed, the person carrying out the work shall give the local authority:A. A notice which specifies:i. The Target CO₂ Emission Rate for the building, calculated and expressed in accordance with the methodology approved pursuant to Regulation 24.ii. The CO₂ Emission Rate for the building as constructed, calculated and expressed in accordance with the methodology approved pursuant to Regulation 24.iii. Whether the building has been constructed in accordance with the list of specifications referred to in paragraph 2(C), and if not, a list of any changes to those specifications.ORB. A certificate of the kind referred to in paragraph (4), accompanied by the information referred to in sub-paragraph (A).

(4) A local authority is authorized to accept, as evidence that the requirements of Regulation 26 have been satisfied, a certificate to that effect by an energy assessor who is accredited to produce Energy Performance Certificates for that category of building.

(5) In this regulation, specifications mean specifications used for the calculations of the CO₂ Emission Rate.

Regulation 27A – Fabric Energy Efficiency Rate Calculations

(1) This regulation applies where a dwelling is erected and Regulation 26A applies.

(2) Not later than the day before the work starts, the person carrying out the work shall give the local authority a notice which specifies:A. The Target Fabric Energy Efficiency Rate for the dwelling, calculated and expressed in accordance with the methodology approved pursuant to Regulation 24.B. The Fabric Energy Efficiency Rate for the dwelling as designed, calculated and expressed in accordance with the methodology approved pursuant to Regulation 24, andC. A list of specifications to which the dwelling is to be constructed.

Point 3Not later than 5 days after the work has been completed, the person carrying out the work shall give the local authority:A. A notice which specifies:i. The Target Fabric Energy Efficiency Rate for the dwelling, calculated and expressed in accordance with the methodology approved pursuant to Regulation 24.ii. The Fabric Energy Efficiency Rate for the dwelling as constructed, calculated and expressed in accordance with the methodology approved pursuant to Regulation 24.iii. Whether the dwelling has been constructed in accordance with the list of specifications referred to in paragraph 2(C), and if not, a list of any changes to those specifications.

ORB. A certificate of the sort referred to in paragraph 4, accompanied by the information referred to in sub-paragraph A.

Point 4A local authority is authorized to accept, as evidence that the requirements of Regulation 26A have been satisfied, a certificate to that effect by an energy assessor who is accredited to produce Energy Performance Certificates for that category of building.

Point 5In this regulation, specifications means the specifications used for the calculations of the Fabric Energy Efficiency Rate.

Now off to Regulation 27C – Target Primary Energy Rate Calculations for New Buildings

Point 1This regulation applies where a building is erected.

Point 2Not later than the day before the work starts, the person carrying out the work must give the local authority a notice which specifies:A. The Target Primary Energy Rate for the building, calculated and expressed in accordance with the methodology approved pursuant to Regulation 24.B. The calculated Target Primary Energy Rate for the building as designed, calculated and expressed in accordance with the methodology approved pursuant to Regulation 24.C. The list of specifications to which the building is to be constructed.

Point 3Not later than 5 days after the work has been completed, the person carrying out the work must give the local authority:A. A notice which specifies:i. The Target Primary Energy Rate for the building, calculated and expressed in accordance with the methodology approved pursuant to Regulation 24.ii. The calculated Target Primary Energy Rate for the building as constructed, calculated and expressed in accordance with the methodology approved pursuant to Regulation 24.iii. Whether the building has been constructed in accordance with the list of specifications referred to in paragraph 2(C), and if not, a list of any changes to those specifications.

ORB. A certificate of the sort referred to in paragraph 4, accompanied by the information referred to in sub-paragraph A.

Point 4A local authority is authorized to accept, as evidence that the requirements of Regulation 26C have been satisfied, a certificate to that effect by an energy assessor who is accredited to produce Energy Performance Certificates for that category of building.

Point 5In this regulation, specifications means the specification used for the calculations of the Target Primary Energy Rates.

So, what are these all about, you ask?

In the opinion of the Secretary of State, a building is a nearly Net Zero Energy building if:

• it meets the Target Emission Rate required by Regulation 26, and

• it is analyzed whether alternative high-efficiency systems could be used and be feasible for the building — analysis in line with Regulation 25A.

Regulation 24(4) simply tells us that the Secretary of State needs to approve a methodology of assessment — and this is widely known as the Standard Assessment Procedure, otherwise known as SAP in short.

Regulation 25 requires the Secretary of State to approve minimum targets for Primary Energy Rates, Emission Rates, and Fabric Energy Rates — and these rate calculations will be needed for the new dwelling in line with Regulations 26, 26A, and 26C.

Regulations 27, 27A, and 27C cover the notification to building control and the calculation of energy performance both prior to and after the building is built.

So, Section 1 is all about calculating the Target Primary Energy Rate, Target Emission Rate, and Target Fabric Efficiency Rate — the so-called Total Energy Performance.

It is done by comparing the calculations of the actual dwelling against a so-called notional dwelling before and after the construction.

A notional dwelling is simply the proposed dwelling in shape and size, but with the accepted performance of fabric and services and as such, the building needs to hit that minimum in the specification.

The government set out a Standard Assessment Procedure — SAP in short — to deal with that requirement.The Target Primary Energy Rate is measured in kilowatt-hours per square metre.The Target Emission Rate is measured in kilograms of CO₂ per square metre.The Target Fabric Energy Efficiency Rate is measured in kilowatt-hours per square metre.

The full specification of figures used in SAP can be found in the SAP Appendix R.So, every new dwelling will need to have these parameters calculated using SAP.

It typically means that:

• Thermal fabric opening area should not exceed 25% of the total floor area.

• Walls should have a U-value of 0.18 W/m²·K, except for party walls — which should be 0.0.

• Floors should have a U-value of 0.13 W/m²·K.

• Roofs should have a U-value of 0.10 W/m²·K.

• Roof windows should have a U-value between 1.2 and 1.7 W/m²·K, depending on the angle of the roof window.

• Windows and doors should have a U-value of 1.2 W/m²·K when there's more than 60% glazed area, otherwise 1.0 W/m²·K.

• Air permeability should be a maximum of 5 m³/hr·m² at 50 Pascals, with natural ventilation and intermittent extract fans.

There are also minimum specifications for the heating source, whether gas, heat pump, or district network.Different heating systems and hot water systems — including heat recovery — apply.

Lighting must have a maximum total capacity of 15500 + (85 × the floor area in lumens), with efficiency of 80 lumens per watt.

There is a requirement for PV systems of at least just over 6% of the ground floor area in dwellings, and similarly for flats — only scaled by the number of stories, with installation facing southeast to southwest.

All these ratings — when taken for a building containing multiple dwellings (typically flats and terraced houses) — can be averaged using a weighted average of values by simply adding all the targets and dividing them by the sum of all floor areas.

Section Two deals with calculations of the actual project:

• Dwelling Primary Energy Rate,

• Dwelling Emission Rate, and

• Dwelling Fabric Energy Efficiency Rate.

All these need calculation before the project starts, and then must be compared with what has actually been built, in correlation with the air permeability of the building.

The building control body needs notification on all these rates and how they compare between the target and design values, including what specification has been used in the calculation.That can be done using the BRA report — that is, the Building Regulations Part L Compliance Report, which is shown in Appendix B of the document.

This notification needs doing:

• before shovels hit the ground, and

• again with the as-built values and photographic evidence following the construction.

When the building contains multiple units, we can either use each unit's value individually, or use the average values for all of them.

The emission value and primary energy rate calculation may be complicated a bit further with the use of additional heating sources, and the value should be reached by considering the percentage input of the two different sources set in that space.

For heat networks, we need to calculate the CO₂ and primary energy factor to use in our calculations, and the factor will equally apply to both target and designed values.We need to make sure enough heat can be delivered to the house and that the network has the capacity to do it.The building control will need evidence of both.

When connected to a new district heat network, we need to calculate all the heat sources used up to the end of the year 2027.If there is a change of the heat source, the building control will need to be notified of such, and the notification should consist of:

• the planning permission (if required), and

• the contract for the new heat source.

Swimming pools and basins do not need to be treated differently.No special consideration for the basins is required.The area of the pool should be treated as a floor with performance matching that used for the creation of the pool.

For the calculation U-value:

• Party walls will be generally 0.0 for solid walls and fully filled cavity walls,

• 0.2 for sealed and filled cavity walls, and

• 0.5 for unsealed, unfilled cavity walls.

Fixed lighting will have an impact on the calculations of energy and emissions rates.

To satisfy the requirements of Target Energy Rate and Emission Rate, we need to follow:

• Fabric efficiency, combined with

• Efficient building services,

• Integrated with zero-carbon technologies.

But only fabric efficiency is relevant when we deal strictly with the fabric Energy Efficiency Rate

Now we are off to Regulation 25A, which deals with the consideration of high-efficiency alternative systems.

Let’s start with the wording of the legislation:

Consideration of High-Efficiency Alternative Systems for New Buildings — Regulation 25A

Point 1Before construction of a new building starts, the person who is to carry out the work must analyze and take into account the technical, environmental, and economic feasibility of using high-efficiency alternative systems — such as the following systems — in the construction, if available:A. Centralized energy supply systems based on energy from renewable sources.B. Cogeneration.C. District or block heating or cooling, particularly where it is based entirely or partially on energy from renewable sources.D. Heat pumps.

Point 2The person carrying out the work must:A. Not later than the beginning of the day before the day on which the work starts, give the local authority a notice which states that:i. The analysis referred to in paragraph 1(A) has been undertaken,ii. Is documented, andiii. The documentation is available to the authority for verification purposes.B. Ensure that a copy of the analysis is available for inspection at all reasonable times upon request by an officer of the local authority.

Point 3An authorized officer of the local authority may require production of the documentation in order to verify that this regulation has been complied with.

Point 4The analysis referred to in paragraph 1:A. May be carried out for individual buildings, for groups of similar buildings, or for common typologies of buildings in the same area.B. Insofar as it relates to collective heating and cooling systems, may be carried out for all buildings connected to the system in the same area.

Point 5In this regulation:A. Cogeneration means simultaneous generation in one process of thermal energy and one or both of the following:i. Electrical energy,ii. Mechanical energy.B. District or block heating or cooling means the distribution of thermal energy in the form of steam, hot water, or chilled liquids from a central source of production through a network to multiple buildings or sites for the use of space or process heating or cooling.C. Energy from renewable sources means energy from renewable non-fossil sources — namely wind, solar, aerothermal, geothermal, hydrothermal and ocean energy, hydropower, biomass, landfill gas, sewage treatment plant gas, and biogases.D. Heat pump means a machine, device, or installation that transfers heat from natural surroundings — such as air, water, or ground — to buildings or industrial applications by reversing the natural flow of heat so that it flows from a lower to a higher temperature. For reversible heat pumps, it may also move heat from the building to the natural surroundings.

The Secretary of State is happy when we analyze the feasibility of such systems, following Section 3. However, it is all about a reasonable approach. There is no expectation for us to use solutions that are not feasible at the moment.

So what does Section 3 say?

It concentrates on the consideration of high-efficiency alternative systems, which we need to have and have it documented for the inspection of building control.Just saying that you have considered it and that it was not feasible will not suffice.

This also applies to buildings under major renovations, where the technical, environmental, and economic feasibility of such a system needs to be evaluated.

Now, to satisfy Requirement L1(a) in new buildings, we need to prevent the building from gaining or losing too much heat.This will be achieved by addressing:

• Building fabric

• Airtightness

• Pipework insulation

In the case of heat gain, we follow the recommendations of Section 4.

In the case of existing buildings and extensions, we need to follow the recommendations of Sections 10, 11, and possibly even 12 — making the building airtight and insulating the pipework.

Section 4 deals with the limitation of heat gains and losses.

Think U-values, and think about them in terms of the entire element and the way it is considered in the Building Research Establishment paper BR 443.

U-values for windows and doors can either follow:

• The actual configuration (as built),

• A standard type as considered by the document, or

• Use the Hot Box method to BS EN ISO 12567.

Glass and Glazing Federation documents are also very helpful, or you can use figures from SAP Table 6E.

The section gives us the limiting values for new buildings for different elements — but truth be told, these are lesser than the target values anyway, so they will rarely be taken into consideration.

On the other hand, limiting standards in existing dwellings for new and replacement elements will be very much appropriate to use:

• For roofs, that is 0.55 W/m²·K

• For walls and floors, it is 0.18

• Windows and doors are 1.4

• Roof lights are 2.2

In case you are blessed with a swimming pool, it is 0.25 W/m²·K for the pool basin.

But for renovated and retained elements, that is less — and it will be different for each case.

For renovated elements, they should reach the following:

• Roofs: 0.16 W/m²·K

• Floors: 0.25

• Cavity insulation: 0.55

• Internal/external insulation: 0.30

Retained elements should be upgraded to these values if they are over the threshold limits. These limits are:

• Roofs: 0.35

• Wall insulation: 0.70

Naturally, this will not always be technically or functionally viable or will not lead to a simple payback within the next 15 years.If such is the case, we will need to upgrade the element so it does satisfy these tests, but not to less than the threshold value.

It is important for the insulation to be continuous and tied to avoid unwanted cold spots, thermal bridges, or leaks of heat and air-carried moisture.

To achieve this, we need to think about proper specification — that needs to be buildable, or in other words, achievable on site.And once being built, it needs to be recorded that it actually is well executed, in line with the specified details.

• Floors and foundations: perimeter insulation to be a minimum of 25 mm, and insulation on the damp-proof course should be moisture-resistant and extend to the foundation.

• Windows and doors should be tightly fit in line with BS 8213 and contiguous with the insulation layer.

• Insulated cavity closers are the way to go in cavity wall construction.

• Roof and wall insulation should overlap.

Rigid insulation boards are known to be difficult to fit well, so there is a need for a compensatory measure to be put in place — like a compressible tape when the boards are placed in between the rafters, and low expansion foam in wall cavities.

Any penetrations in the insulation should be addressed by ensuring a tight fit.

Thermal bridging follows similar considerations as for insulation in general — in terms of quality of workmanship, specification for junctions, and keeping of the as-built record.

The emphasis is on the continuity of the insulation or insulation elements — like having insulation under the damp-proof course, at least one block high, to overlap with the insulation of the floor.

The same principle follows for:

• Windows and doors junctions

• Walls

• Floors

• Party walls

• Roof junctions

Thermal bridging should be assessed according to BRE Report 497, to the temperature factor set out in BRE Information Paper 1/06.

We are allowed to use other established details — like those in the Local Authority Building Control Construction Details Library — but then inspection of the details on site will be paramount.

We can also use SAP values or default values given by the document, for example: 0.2 W/m²·K.

When we deal with the existing building, there are no special requirements — but we should still try to improve on the existing whenever possible.

Airtightness in a new dwelling should meet the minimum standard, but care needs to be taken to avoid unnecessary infiltration of cold or hot air.The drawings should show the position and extent of the continuous air barrier.Any penetrations and junctions should be minimized and sealed.

Airtightness in existing dwellings should be improved whenever possible, but care needs to be taken to address the ventilation requirements of the entire dwelling — as over-tightness may lead to condensation issues and combustion heating system issues.

Limitation of heat losses and gains from building services is another consideration of this document.

The document basically tells us to insulate pipes where the loss of heat is the greatest — so, where there is hot water flowing, and it flows through unheated spaces and voids.

Hot water pipes and secondary circulation pipes — heat losses should not exceed the limits put on us in British Standard 5422 for water at 60°C.

The document gives us typical thicknesses for different pipe sizes:

• 5 mm for 10 mm pipe

• 10 mm for 25 mm pipe

• 15 mm for 50 mm pipe

• 20 mm for 100 mm pipe

And the size jumps by five for every doubling.

External district heat network pipes will also require appropriate insulation according to BS EN 253 for pre-insulated pipes, or conventional equivalent of such, and at least as well insulated above ground as it is in-ground.

Hot water cylinders need to perform to ASER maximum heat loss standards, which depend on their size — starting at 1.03 kilowatt-hours per 24 hours for a 50 L cylinder to 3.57 kilowatt-hours per 24 hours for a 1,000 L cylinder.There is an equation to follow if you need to go bigger.

Similar limits apply to heat interface units. Naturally, all types of water storage vessels will need to be up to the code, such as:

• BS 3198 – Specification for copper hot water storage combination units for domestic purposes.

• BS 1566-1 – Copper indirect cylinders for domestic purposes – open vented copper cylinders – requirements and test methods.

• BS EN 12897 – Water supply – specification for indirectly heated unvented storage water heaters.

Moving on to the provision of energy-efficient fixed building services with efficient controls.The Secretary of State is considered satisfied if the system:

• Meets minimum standards,

• Is appropriately sized, and

• Has controls for hot water and heat.

On-site electricity generation should also be properly sized and controllable.

Now, Section 5 deals with general guidance for the minimum building services efficiencies and controls.

We are told that every new fixed building service needs to meet the minimum standard set in Section 6 for a given system.Services outside Section 6 should be treated in a comparable fashion with the ones within.

The efficiency needs to be tested and certified by a notified body.

When we replace a service in an existing house, we need to keep in mind the Section 6 efficiency, but otherwise, we must provide a service that is not less efficient than the existing one in terms of:

• Fuel type,

• CO₂ emissions, and

• Primary energy demand per kilowatt-hour, when changing the fuel type,

There is some leeway in this provision — for example, when we switch to a heat pump of approved standard, or when we deal with a fuel change in a building that loses less than 25 kWh/m² per year.

Renewable heat sources should be changed like-for-like in terms of performance, and the building should be ready to connect to a heat network.

The proper sizing of the heating and hot water system should take into consideration:

• The heat loss calculation for the dwelling, and

• Sizing methodology that accounts for the building’s properties.

The Approved Document prefers the Chartered Institute of Plumbing and Heating Engineering – Plumbing Engineering Services Design Guide for this purpose.

Combi boilers should be able to modulate down their heat output to the level generally required by the dwelling.

New wet heating systems need to be sized to meet the requirement of low-temperature heating, with flow temperatures of 55°C maximum.That also applies to entirely new systems in existing dwellings.

This will not always be feasible, and whenever it is not, we need to size the system so it turns at the minimum that becomes feasible.

Domestic hot water systems should be sized in line with the needs of the building, and can follow:

• BS EN 12831-3 standards, or

• The Plumbing Engineering Services Design Guide.

And the system should not be significantly oversized.

Heat pumps should be specified so they meet the needs of the dwelling without relying on additional electric heat being supplied to the system.Likewise, the reversible heat pump should be optimized for heating rather than cooling.

Now, controls of the system:

We should consider splitting wet heating systems for new dwellings over 150 m².The system should switch off automatically if not in use.

Hot water storage-supplied systems should have:

• Electric temperature control, and

• A time control that is independent of space heating circuits.

Hot water circuits should have fully pumped circulation when it is compatible with the heat generator.

Space heating should have temperature control for the heating appliance, and wet heating systems should ensure minimum flow of water to avoid short cycling.

Thermostatic room control should be fitted in every room, unless it is imprudent or not feasible.

The Secretary of State considers it imprudent when:

• At least 70% of the zone is an open-plan living space, or

• In a group of two adjacent, similar-use rooms being considered together.

We may satisfy the requirement of control by either:

• Installing thermostatic control over each heat emitter — such as thermostatic radiator valves, or

• A thermostat in the room served by the given circuit, but do not provide both at the same time — either a thermostat for individual rooms or heating zones, or individual network heat emitter control for each emitter.

When it comes to the control of existing heating and hot water systems, it should follow the previous considerations. But if, in the existing state, both water and heating are controlled together, this may continue.

A boiler interlock should be introduced if there is work done to the system with a boiler.

Hot water cylinders, if replaced, should have an electronic temperature control, and the new boiler should have boiler controls in line with Section 6 expectations.

Now, what is hiding in Section 6?

In this section, we come to find out more details about the expected performance of the systems installed in the dwellings — including for the energy generation.

The document also points us to the Ecodesign for Energy-Related Products Regulations 2010. In case this is applicable, this also applies to our new systems.

The document gives us the minimum standards, but it may be the case that this minimum will need to be improved when considering the dwelling holistically.

Starting with gas-fired heating systems in new dwellings:

• Wet heating should be at least 92% efficient, according to the ErP efficiency (Energy-related Products Directive).

But in existing buildings, this becomes convoluted and will generally be different for different types of heaters.So, wet heating remains at 92% efficiency to ErP rating, but may be as low as 78% according to SEDBUK 2009.

We’ve got two ways of measuring efficiencies:

• ErP, which stands for Energy-related Products Directive

• SEDBUK, which stands for Seasonal Efficiency of Domestic Boilers, UK

The data for all other types of heaters can be read from the table in the document. It includes:

• Warm air heating intended for space heating applications

• Inset live fuel-effect heaters

There are also other aspects to consider, such as:

If we install a combi boiler in an existing dwelling, we should make it operate more efficiently by either:

• Recovering the flue gas heat,

• Measuring the external weather and compensating for it with load control, or

• Simply compensating for the internal load in the system depending on the actual requirement of the dwelling.

But I think the simplest one of them all is a smart thermostat.I personally have not seen one of these [types] in action, but…

Should you consider replacing or installing a new range cooker with an integrated gas boiler, the cooking and heating burners should be separate.

Either gas-fired warm air systems or independent heating appliances should be:

• Controllable, and

• Automatically adjustable to the temperature of the space they serve.

These appliances should meet appropriate standards, such as:

• BS EN 12666 – Independent gas-fired convection heaters incorporating a fan to assist transportation of combustion air and/or flue gases

• BS 7977 – Specification for safety and rational use of energy of radiant convective appliances

• BS EN 613 – Independent closed-fronted gas fires (Type B11, Type C11, Type C31, and Type C91 heaters)

• BS EN 13278 – Open-fronted gas-fired independent space heaters

• BS EN 14829 – Independent gas-fired flueless space heaters for nominal heat input not exceeding 6 kW

• BS EN 449 – Specification for dedicated liquefied petroleum gas appliances (domestic flueless space heaters, including diffusive catalytic combustion heaters)

• BS EN 509 – Decorative fuel-effect gas appliances

Interestingly, we are not allowed to have more than one decorative-effect gas fire per 100 m² installed in our dwellings.

Now, on to oil-fired heating systems:

The requirements are similar to those of gas heating systems. Again, we deal with efficiencies either to ErP or SEDBUK, as set within the document.

For example:

• Wet heating with regular boilers should be 91% ErP or 84% SEDBUK.

Electric space heating systems:

These are considered 100% efficient, so no efficiency limits are given.

However, for electric storage heaters, we need to be able to control both the input charge and the heat release.

Electric panel heaters or electric warm air systems also need control — either for each room or for each appliance.

But check the requirements of Section 5, so as not to go too crazy with the amount of control needed.

Solid fuel heating systems:

These are categorized by designation, and accordingly should have minimum efficiency measured in calorific value.

Appliances forming part of the central heating system, delivering primary heat and belonging to any of the following categories:D1 to D4, F, G2, G, J2, or J5, should meet the requirements of Section 5:

• Have separate time controls for space heating and hot water circuits.

• Have automatic control of the burning rate.

• Have factory-required heat leak radiator installed.

An appliance that is part of the central heating system should be one of the D, F, G, O, J categories, and have the ratio of room heat to water heat set to be satisfactory to meet the needs of the property.

District Heat Networks and Community Heating Systems

The considerations in this part are for distribution networks of at least 15 dwellings, with a central heat source — whatever that may be:

• Boiler,

• Combined Heat and Power unit (CHP), or

• Heat pumps.

But whatever it is, if it’s a new district heat network, it needs to comply with Section 6 of Approved Document L Volume Two, which deals with buildings other than dwellings.

Now, if we are connecting to an existing network, depending on whether it’s a new dwelling or an existing one, we will face different limits.

So, for a new dwelling, the emission factor for delivered heat should be under 0.35 kg CO₂ per kWh.You can get this value either from a SAP calculation or the Product Characteristics Database.The value should be the same as used in the calculation for the dwelling emission rate.

Connecting an existing dwelling will usually mean changing the fuel source, so the appropriate paragraph of Section 5 should be followed. But in essence, it should improve the circumstances of the dwelling to be approved.

The emission factor and primary energy factor for the house need to be established.

The pumps of the system should have variable volume control to adjust to the requirements of the system, and an appropriate temperature difference for the primary heating circuit of at least 20°C (for fuel-heated networks).Heat pump networks may work at lower temperature differences.

Dwelling input should be controlled with:

• Balancing valves,

• Control of maximum flow rate into the building’s wet heating system, and

• Variable volume controls for the hot water system.

All heat exchange should be measured by an appropriate meter for each dwelling.

Micro Combined Heat and Power (Micro-CHPs)

It is important to ensure the micro-CHP heating emission rate is not greater than that of the regular boiler using the same fuel as the CHP.

The emission rate should be established using: the DEFRA method, or to evaluate the annual energy performance of microgeneration heating systems in dwellings. BSI PAS 6067 together with the plant size ratio for a temperature difference of 24.2°C, calculated as CRA = measured heat output / heat loss of the building.

Considerations for Underfloor Heating Systems

• They should have temperature-adjustable zones.

• If the system is electric, the room thermostat should have a manual override.

• Heating systems of floor screeds greater than 65 mm thick should:

  • Automatically reduce heating at night, or

  • When the room is not in use.

• Heat loss should be minimized.

To minimize heat loss:

• The floor should be insulated to limit heat loss to no more than 10 W/m², calculated by taking the U-value of the floor times 10.

• We need to provide separation between the heating system and the structure of the floor, giving at least 1.25 m²·K/W of resistance — or R-value of 1.25 — for systems intended for intermittent or cyclic operation and installed over unheated rooms.

To reduce downward heat transfer in intermediate floors, the layer of insulation should be at least:

• 10 W/m² or

• U-value of 0.5 for electric systems, or

• U-value of 0.75 for wet systems.

Distribution pipework should be insulated to the standards of Section 4.

For electric underfloor heating systems up to 60 mm screeds:

• The direct systems and the night storage systems are the ones with screeds of 65 mm and over.

If a night storage system is installed, we need to have a quick way of heating the house, and this should:

• Be able to heat at least 20% of the floor area of the dwelling, and

• Have control of room thermostat and floor temperature sensing.

In any case, a programmable thermostat with an override feature and floor sensing should be in place for control of the operation of the electric system.

Heat Pump Heating Systems

As you know, heat pumps can be used for heating, but also for cooling — and the cooling provision will follow later on.

For heating, though, they need to have certain efficiencies:

• A minimum Coefficient of Performance (COP) of 3 for heating, and

• A minimum COP of 2 for hot water.

So they should be able to multiply the energy input of the system.

If the system is small enough — under 22 kilowatts — the regulations for Ecodesign, Commission Regulation (EU) No. 2016/2281 will apply.

As ever, being an appliance, the heat pump will fall under the provisions of Section 5 considerations.We should also be able to control:

• The water pump,

• Air or water temperature,

• Fan operation,

• Defrosting of the heat exchanger,

• Secondary heating, if fitted, and

• Have protection from water and airflow failure, high water or refrigerant temperature.

We should be able to control this operation with a timer or programmer for space heating, and have weather compensation or internal temperature control fitted.

If heat pumps are provided in addition to other heat sources, they should all be incorporated into one control system.

The legislation reminds us about the placement of the heat pump and the importance of reading the manufacturer’s instructions.The most troublesome aspect of wrong placement will be:

• Falling effectiveness of the pump,

• Problems with recirculation of cold exhaust air, and

• Removal of condensation from the outer coil during defrosting.

Issues from the use of the unit — like noise and vibration — can also be a problem, so we need to think carefully about where it’s placed and how to mitigate it.We will also be bound by planning regulations on this front.

Solar Heating / Solar Water Heating Systems

The document considers systems where:

• The solar collector area is less than 20 m², and

• It supplies a storage tank of not more than 440 L.

The system needs to be tested to:

• BS EN 12975-1 and

• BS EN ISO 9806 for thermal performance and documentation.

The pump for the collector should be:

• Less than 50 watts, or

• 2% of the peak thermal power of the collector (whichever is more applicable).

The ratio for the heat exchanger area to absorber area should be 10.

The system should be controlled to:

• Maximize the use of solar power and use it first, before boosting by other heat sources, and

• Mitigate the adverse effects of excessive temperatures and pressures.

The hot water storage vessel should be at least either:

• 25 m² per 1 m² of the net absorber area, or

• 80% of the daily hot water need for the dwelling.

Comfort Cooling

The cooling system should be based on the heat gain calculations for the dwelling and not exceed 120% of the calculated cooling load.We can calculate the load using:

• CIBSE Guide A, and

• Manufacturer data.

The Seasonal Energy Efficiency Ratio (SEER) of the unit should be 4 or more.Control for timing and temperature should be provided for each control zone and terminal unit.

If heating is also provided in the room, it should be prevented from operating simultaneously with cooling.

The refrigeration pipework should be insulated and housed in protective trunking.

Cooling systems serving more than one dwelling should follow the recommendations of Volume Two of this document.

Mechanical Ventilation

We’ve heard about this one before when we discussed ventilation requirements for dwellings — so we know how to ventilate already.But now, we must ensure we don’t use too much energy to do it — so we are faced with efficiencies here as well.

Units extracting air intermittently or continuously should have:

• An efficiency of 0.5 watts per litre per second for intermittent,

• 0.7 watts per litre per second for continuous.

Continuous supply systems should also be at 0.5 watts per litre per second.

A combination of extraction and supply should have a heat recovery system with at least:

• 73% efficiency,

• Must be bypassable,

• Controllable during summer, and

• Use no more than 1.5 watts per litre per second.

Lighting

The space should not be overly illuminated (but let’s face it, you'll buy your own lightbulb).

The efficiency of the lamp should be at 75 lumens per watt.

Lamps should be:

• Functional for the space or zone, and

• Controllable.

External lighting must be:

• Automatic, if the efficiency is worse than 75 lumens per watt, or

• Manual control is fine, if it meets or exceeds that threshold.

Building Automation and Control Systems

The document does not go into too much detail, apart from requiring that systems be proper.

If the building is large and complex, then Volume Two considerations may apply.

On-Site Electricity Generation and Storage

It needs to be:

• Sized properly for the site and demand,

• Installed following the manufacturer’s instructions.

If replacing an existing system:

• The efficiency or capacity should be at least the same as the existing system —

  
  

  unless the dwelling’s needs can still be satisfied with a different configuration.

The system should be able to control itself automatically.

So, off to Section 7, which deals with the requirements of Regulation 43: Pressure Testing.

Let us start with the text of the legislation.

Pressure Testing — Regulation 43

Point 1This regulation applies to the erection of a building in relation to which paragraph L1(a)(i) of Schedule 1 imposes a requirement.

Point 2Where the regulation applies, the person carrying out the work shall, for the purpose of ensuring compliance with Regulation 26, Regulation 26A, and paragraph L1(a)(i) of Schedule 1:A. Ensure that:i. Pressure testing is carried out in such circumstances as are approved by the Secretary of State, andii. That testing is carried out in accordance with a procedure approved by the Secretary of State; andB. Subject to paragraph 5, give notice of the results of the testing to the local authority.

Point 3The notice referred to in paragraph 2(B) shall:A. Record the results and the data upon which they are based, in the manner approved by the Secretary of State, andB. Be given to the local authority not later than 7 days after the final test is carried out.

Point 4A local authority is authorized to accept as evidence that the requirements of paragraph 2(A)(ii) have been satisfied a certificate to that effect by a person who is registered by:

• Elmhurst Energy Systems Ltd, or

• The Air Tightness Testing and Measurement Association,

  
  

  in respect of pressure testing for the air tightness of buildings.

Point 5Where such a certificate contains the information required by paragraph 3(A), paragraph 2(B) does not apply.

The Secretary of State is satisfied if the dwelling passes the pressure test as described further in this section.

The test should be done on each and every dwelling.

The maximum rate of air leakage at 50 Pascals needs to be established using properly calibrated equipment by a trained and registered individual.

Building control will require proof of test certification, equipment calibration, and individual credentials.

The following must be recalculated using the test results to check if they meet the targets:

• Energy rate,

• Dwelling emission rate, and

• Fabric Energy Efficiency rate.

The report on test attempts should be included in the building control submission — failures included.

The test should be done to CIBSE TM23 — Testing Buildings for Air Leakage.

Section 8 – Commissioning and Regulations 44 and 44ZAA.

Regulation 44 – Commissioning

Point 1This regulation applies to building work in relation to which paragraph F1(2) of Schedule 1 imposes a requirement,but does not apply to the provision or extension of any fixed system for mechanical ventilation or any associated controls where testing and adjustment is not possible.

Point 2This regulation applies to building work in relation to which paragraph L1(b) of Schedule 1 imposes a requirement,but does not apply to the provision or extension of any fixed building service where testing and adjustment is not possible or would not affect the energy efficiency of that fixed building service.

Point 3Where this regulation applies, the person carrying out the work shall, for the purpose of ensuring compliance with paragraph F1(2) or L1(b) of Schedule 1, give the local authority a notice confirming that the fixed building services have been commissioned in accordance with a procedure approved by the Secretary of State.

Point 4The notice shall be given to the local authority:A. Not later than the date on which the notice required by Regulation 16(4) is to be given, orB. Where that regulation does not apply, not more than 30 days after completion of the work.

Regulation 44ZAA – Commissioning in Respect of a System for On-site Electricity Generation

Point 1This regulation applies to building work in respect of a building in relation to which paragraph L2 of Schedule 1 imposes a requirement,but does not apply to the provision or extension of any system for on-site electricity generation where testing and adjustment is not possible.

Point 2Where this regulation applies, the person carrying out the work must, for the purpose of ensuring compliance with paragraph L2 of Schedule 1, give to the local authority a notice confirming that the system for on-site electricity generation has been commissioned.

Point 3The notice must be given to the local authority:A. Not later than the date on which the notice required by Regulation 16(4) is to be given, orB. Where that regulation does not apply, not more than 30 days after completion of the work.

In the gist, fixed building services need to be commissioned to assure that operation is good and proper.

This involves the formation of a commissioning plan that identifies:

• What is being tested and how,

• What does not require testing, and

• Why it is excluded.

It forms part of your submission to building control.

Notice of completion will generally follow the 5-day requirement upon completion, but could be up to 30 days when done by a person registered in the competent person scheme.

It will need to include confirmation of following proper procedures, including the commissioning plan, and give assurance of reasonable performance.

It is rather pertinent to have that notice done, as building control may withhold the completion certificate until it is.

Now going system by system:

• Hot water systems should be prepared and commissioned to BS 7593.

  
  

  The system should be:

  • Cleaned and flushed out,

  • Include chemical inhibitors in the primary heating circuit to protect against scale and corrosion.

    
    

    In hard water areas, we may need to treat the water to maintain the system.

• Heat pumps should be commissioned according to manufacturer specifications and system design parameters.

  • Ground arrays should be flushed and purged to get rid of debris and air.

  • That flushing should be done separately from the heat pump system, which will require the same in isolation from the array.

  • Cleaning and purging should be followed by a pressure test to BS EN 805.

  • Antifreeze and biocide should be added to the heat exchangers as appropriate.

  • Commissioning information needs to be provided to the dwelling owner and should include the details of the fluid and its commissioned concentration.

• For community heating systems, they should be commissioned to optimize the use of energy for pumping and flow rates.

  • Individual heat emitters should be balanced, either using calibrated control valves or appropriate return temperature.

  • Underfloor heating commissioning should be done to BS EN 1264-4.

Section 9 covers the necessity of providing information about the system, including Regulations 40 and 40A.

Let’s start with the legislation:

Regulation 40 – Information About the Use of Fuel and Power

Point 1This regulation applies where paragraph L1 of Schedule 1 imposes a requirement in relation to building work.

Point 2The person carrying out the work shall, not later than 5 days after the work has been completed, provide to the owner sufficient information about:

• The building,

• The fixed building services, and

• Their maintenance requirements,

so that the building can be operated in such a manner as to use no more fuel and power than is reasonable in the circumstances.

Regulation 40A – Information About Assistance for On-site Generation of Electricity

Point 1This regulation applies to building work in respect of a building in relation to which paragraph L2 of Schedule 1 applies.

Point 2The person carrying out the work must, not later than 5 days after the work has been completed, provide to the owner sufficient information about the system for on-site electricity generation in respect of:

• Its operation, and

• Maintenance requirements,

so that the system may be operated and maintained in such a manner as to:

• Produce the maximum electricity that is reasonable in the circumstances, and

• Deliver the electricity to the optimal place for use.

In short:The owner needs to know how to operate and maintain the system, and what work has been done.

The operating and maintenance instructions should be:

• Easy to understand,

• Site-specific,

• Detailed, and

• Accessible.

They should:

• Describe the system with its location on the floor plan,

• Identify components and explain their function,

• Explain how to operate and maintain them,

• Direct users to important documents, and

• Include commissioning sheets, where relevant.

In addition, new buildings should have an accompanying BRA Report with:

• Photographic evidence of the build quality,

• All the as-used energy pertinent data,

• The Energy Performance Certificate, together with recommendations.

A Home User Guide should also accompany new dwellings, and contain provisions for:

• Ventilation,

• Heating,

• Domestic hot water,

• On-site electricity generation,

• Staying cool in hot weather.

In existing buildings, if Section 5 and/or 6 apply, the installation of the fixed building service should be:

• Energy performance assessed, and

• Documented.

When the entire system is involved, we will comply by either:

• Providing the full record of commissioning, in line with Section 8 requirements, or

• Submitting the SAP assessment and Energy Performance Certificate (EPC) or similar.

However, if work on the existing system alters the energy performance or CO₂ emissions of the system — work like changing heating fuel or increasing the system capacity by 25%.

Section 10 deals with the elements in existing dwellings, including extensions.

In addition to Requirement L, we also need to consider Regulation 23(2), the text of which is:

Requirements for the Renovation or Replacement of Thermal Elements — Regulation 23(2)

Where the whole or any part of an individual thermal element is proposed to be replaced, and the replacement:

A. Constitutes a major renovation, orB. In the case of part replacement, amounts to replacement of more than 50% of the thermal element surface area, the whole of the thermal element must be replaced so as to ensure that it complies with paragraph L1(a)(i) of Schedule 1, insofar as that is technically, functionally, and economically feasible.

In short:The building fabric will need to satisfy the performance given in Table 4.2 for all new and replaced elements.

The opening areas in the fabric of the building should be kept within the 25% of the floor area limit,unless compensation measures are introduced to increase the overall energy efficiency of the dwelling.

Windows and doors may satisfy the performance with appropriate certificates, and will fall under the consideration when the work applies to the controlled fitting — meaning including the frame of the element.

When such controlled fitting is changed, we also need to think about:

• Draught-proofing, and

• Installing cavity closers, if appropriate.

For extensions, similar expectations apply, following:

• Table 4.2 for new and replacement elements, and

• Table 4.3 for adopting the existing fabric.

This should be our first point of check.

The total area of openings in extended spaces is again:

• 25%, plus

• All the openings that no longer exist due to the creation of the extension.

Fixed services in the extension should, however, follow Section 5 and Section 6 requirements.

The openings can also be justified by:

• Comparing the area-weighted U-value of the elements that follow the 25% plus existing openings consideration.

  
  

  (Simply add up all the element areas × their U-values, divide by the sum of the areas, and compare the result.)

• Or we can also use SAP calculations for the entire building, plus the notional extension.

When it comes to conservatories and porches, these may be treated separately from the dwelling if:

• They are separated by thermal elements, and

• The heating system is not extended into them.

If they’re not excluded from the energy efficiency requirements due to exceeding a certain size and location,they should still have:

• Thermal elements of sufficient performance, and

• Separate control of the services within.

There is no limit on the amount of glazing for such conservatories and porches.

Now, Regulations 6, 22, and 23(1) deal with:

• Material change of use, and

• Change to energy status.

Starting with the legislation:

Regulation 6 — Requirements Relating to Material Change of Use

Point 1Where there is a material change of use of the whole of a building,such work (if any) shall be carried out as is necessary to ensure that the building complies with the applicable requirements of the following paragraphs of Schedule 1:

A. In all cases:

• B1 – Means of warning and escape

• B2 – Internal fire spread (linings)

• B3 – Internal fire spread (structure)

• B4 – External fire spread (roofs)

• B5 – Access and facilities for the fire service

• C2(c) – Interstitial and surface condensation

• F1 – Ventilation

• G1 – Cold water supply

• G3.1–3 – Hot water supply and systems

• G4 – Sanitary conveniences and washing facilities

• G5 – Bathrooms

• G6 – Kitchens and food preparation areas

• H1 – Foul water drainage

• H6 – Solid waste storage

• J1 to J4 – Combustion appliances

• L1 – Conservation of fuel and power

• P1 – Electrical safety

• S2 – Infrastructure for the charging of electric vehicles

B. In the case of a material change of use described in Regulation 5(c), (d), (e), or (f):

• A1 to A3 – Structure

C. In the case of a building exceeding 15 m in height:

• B4(1) – External fire spread (walls)

D. In the case of a material change of use described in Regulation 5(a), (b), (c), (d), (g), (h), or (i), or where the material change provides new residential accommodation:

• F1(2) – Resistance to contaminants

E. In the case of a material change of use described in Regulation 5(a), (c):

• C2 – Resistance to moisture

F. In the case of a material change of use described in Regulation 5(a), (b), (c), (g), (h) or (i):E1 to E3 – Resistance to the passage of sound.

G. In the case of material change of use described in Regulation 5(e), where the public building consists of or contains a school:E4 – Acoustic conditions in schools.

H. In the case of a material change of use described in Regulation 5(a) or (b):G2 – Water efficiency; andG3.4 – Hot water supply to fixed baths.

I. In the case of a material change of use described in Regulation 5(c), (d), (e) or (j):M1 – Access to and use of buildings otherthan dwellings.

J. In the case of a material change of use described in Regulation 5(a), (b), or (g):Q1 – Security.

Point 2

Where there is a material change of use of part only of a building, such work (if any) shall be carried out as is necessary to ensure that:

A. That part complies, in all cases, with any applicable requirements referred to in paragraph 1(a).

B. In a case in which sub-paragraph B, E, F, G, or H of paragraph 1 applies:That part complies with the requirements referred to in the relevant sub-paragraph.

C. In a case to which sub-paragraph C of paragraph 1 applies:The whole building complies with the requirement referred to in that sub-paragraph.

D. In a case to which sub-paragraph I of paragraph 1 applies:i. That part and any sanitary conveniences provided in or in connection with that part comply with the requirements referred to in that sub-paragraph, andii. The building complies with requirement M1(a) of Schedule 1, to the extent that reasonable provision is made to provide either:

• Suitable independent access to the part; or

• Suitable access through the building to that part.

E. In a case to which sub-paragraph J applies, in respect of material change of use described in Regulation 5(b) or (g):That part complies with the requirement referred to in that sub-paragraph.

Point 3

Subject to paragraph 4, where there is a material change of use described in Regulation 5(k),such work (if any) shall be carried out as is necessary to ensure that any external wall or specified attachment of the building:

• Only contains material of European Classification A2-s1, d0 or A1,

• Classified in accordance with BS EN 13501-1:2007 + A1:2009,

  
  

  titled: Fire classification of construction products and building elements — Classification using test data from reaction to fire tests.

  
  

  ISBN: 978-0-580-98616-5, published by the British Standards Institution on 30 March 2007 and amended in November 2009.

Point 4

Paragraph 3 does not apply to the items listed in Regulation 7(3).

Now off to:

Requirement 22 – Relating to a Change to Energy Status

Where there is a change to a building's energy status,such work (if any) shall be carried out as is necessary to ensure that the building complies with the applicable requirement of Part L of Schedule 1.

Requirement 23.1 – Renovation of Thermal Elements

Where the renovation of an individual thermal element:

A. Constitutes a major renovation, orB. Amounts to the renovation of more than 50% of the element’s surface area,

…the renovation must be carried out so as to ensure that the whole of the element complies with Paragraph L1(a)(i) of Schedule 1,insofar as that is technically, functionally, and economically feasible.

The Secretary of State is satisfied that Requirements 6, 22, and 23.1 are met if we follow the recommendations of Section 11.

Section 11 – Work to Elements of Existing Dwellings

This section covers:

• Renovation of existing thermal elements

• Material change of use

• Change to energy status

It does not deal with new and replacement elements (which was covered in Section 10).

So what is considered renovation?

Renovation is:

• Providing an additional layer in the build-up of the element (e.g. cladding, rendering, dry lining), or

• Replacement of a layer by stripping down to structural components,

• Replacing a waterproof membrane on a flat roof,

• Providing cavity wall insulation.

However, this follows limits of impact, to exclude minor maintenance jobs.The limits are:

• 50% of the surface area of the individual element (wall, roof, or floor) is renovated, or

• 25% of the surface area of the external building envelope (all elements combined) is renovated.

If our work falls under either of these two, we will need to upgrade the whole of the renovated element in line with:

• Table 4.3 of the document, and

• Table C1 in Appendix C.

We also consider material change of use:

• If we turn buildings into dwellings or flats, or

• Change the number of dwellings.

We also consider the change to energy status when the space is turned into space which falls under Energy Efficiency requirements. So, when we change the space, we need to think about the limiting factors for thermal elements, which were previously discussed and are contained within Section Four. If the opening thermal elements are between external unconditioned spaces, they need to be assessed, and if they exceed the U-value limits, they will need to be replaced. The limits are 3.8 W/m²K for roof lights and 3.3 W/m²K otherwise.

In addition to following Section Four recommendations, we need to consider that openings should be no more than 25% of the floor area. Services and their controls should align with the recommendations in Sections Five and Six. Alternatively, if the building contains more than one dwelling, we can use the SAP (Standard Assessment Procedure) to establish the dwelling’s primary energy use and total CO₂ emissions from all dwellings. This may be better than simply following the previous guidance.

That leads us to Regulation 28. In legislation, it says Consequential Improvements to Energy Performance.

Regulation 28,

Point 1, Paragraph 2, applies to an existing building with a total useful floor area over 1,000 m² where the proposed building work consists of or includes:

• an extension,

• the initial provision of any fixed building services, or

• an increase to the installed capacity of any fixed building services.

Point 2: Subject to Paragraph Three, where this paragraph applies, such work or event shall be carried out as is necessary to ensure that the building complies with the requirements of Part L of Schedule One.

Point 3: Nothing in Paragraph Two requires work to be carried out if it is not technically, functionally, or economically feasible — and that’s covered in Section Twelve. It deals with Consequential Improvements of large dwellings of over 1,000 m² of useful floor area, or what is otherwise also called gross floor area.

We are basically told that we may need to upgrade the overall energy efficiency of the dwelling if we extend it, provide fixed building services for the first time, or increase the capacity of any fixed building service. This does not include renewable energy. Naturally, this improvement needs to be technically, functionally, and economically feasible.

For technical guidance, we are referred to Volume Two of this Approved Document, which will be covered in the next episode.

So this is it, folks — the Approved Document L: Conservation of Fuel and Power, Volume One – Dwellings.

Let’s sum it up, section by section:

Section One outlines the process of calculating the total energy performance for new dwellings by comparing them to a notional dwelling using the Standard Assessment Procedure (SAP). Key metrics include the Target Primary Energy Rate, Target Emission Rate, and Target Fabric Energy Efficiency Rate, with specific requirements for thermal fabric, ventilation, heating systems, and lighting. For buildings with multiple dwellings, these targets are averaged based on floor areas.

Section Two covers the calculation of actual energy performance metrics for a dwelling, including the Primary Energy Rate, Emission Rate, and Fabric Energy Efficiency Rate, which must be compared against target values. These calculations — required before and after construction — are documented in the BRE Report and submitted to Building Control, including any adjustments for additional heating sources or heat networks. Special considerations include U-values for different wall types and the impact of fixed lighting, with a focus on integrating fabric efficiency and low-carbon technologies to meet energy and emission targets.

Section Three states that, before starting construction on new buildings, an analysis of the feasibility of using high-efficiency alternative systems — such as renewable energy, cogeneration, district heating or cooling, and heat pumps — must be conducted, documented, and submitted to the local authority. This analysis, which must be available for inspection, applies to individual or groups of buildings and includes both new constructions and major renovations. The key requirement is that the analysis is documented and shows reasonable consideration of these systems, regardless of whether they are ultimately implemented.

Section Four outlines the limitations on heat gains and losses in buildings, emphasizing U-values for various elements — walls, roofs, floors, windows, and doors — and the importance of continuou insulation to prevent thermal bridging. It specifies minimum U-values for new and existing dwellings, with stricter standards for renovated and retained elements, and requires that airtightness and proper insulation be maintained to meet energy efficiency standards.

Section Five mandates that all new and replacement building services meet minimum efficiency standards and be appropriately sized, with a focus on low-temperature heating systems and controls to prevent energy waste. The system should be designed to match the specific heating and hot water needs of the building, with controls such as thermostats and timers to optimize performance. In existing buildings, efficiency upgrades should adhere to these standards, ensuring that heating and hot water systems are not oversized and are equipped with proper controls to enhance energy efficiency.

Section Six outlines detailed performance standards for various heating, cooling, ventilation, and energy generation systems in dwellings. It emphasizes the need for high efficiency in new and existing systems, with specific requirements for gas, oil, electric, and solid fuel heating, as well as heat pumps, solar water heating, and comfort cooling. Each system must meet or exceed minimum efficiency standards, be appropriately controlled, and be sized according to the dwelling's needs. Additionally, the section covers considerations for district heating, underfloor heating, mechanical ventilation, lighting, and on-site electricity generation — ensuring all systems operate efficiently and effectively within the building's overall energy framework.

Section Seven mandates pressure testing for all new dwellings to show compliance with regulations on energy performance, specifically limiting air leakage. Tests must be conducted by certified professionals using calibrated equipment, with results submitted to building control within 7 days. Compliance is confirmed through recalculating energy emission and fabric efficiency rates based on the test outcomes.

Section Eight mandates the commissioning of fixed building services and on-site electricity generation systems to ensure proper operation and compliance with regulations. A commissioning plan detailing the test procedures must be submitted to building control, with a notice confirming completion required within up to 30 days. Specific systems like hot water heat pumps, community heating, and underfloor heating must adhere to these designated standards and procedures, including system cleaning, flushing, and appropriate chemical treatments.

Section Nine requires that within 5 days of completing building work, the owner must be provided with clear, detailed information about the operation and maintenance of the building's fixed services and any on-site electricity generation systems. This information must include system descriptions, maintenance instructions, and commissioning details. New buildings also require a BREL report and an Energy Performance Certificate (EPC). For existing buildings, any significant changes affecting energy performance or CO₂ emissions must be documented and assessed according to relevant standards.

Section Ten mandates that any new or replacement thermal element in existing dwellings must meet performance standards outlined in Table 4.2. Major renovation or replacement involving over 50% of an element’s surface area requires full compliance with these standards, as far as technically and economically feasible. Extensions must adhere to similar performance criteria and ensure that the total area of openings does not exceed 25% of the total floor area, with specific attention to fixed services and their extensions. Conservatories and porches can be treated separately if they have their own thermal elements and controls, but must still meet performance requirements if they are integrated into the main dwelling.

Section Eleven: When a building undergoes a material change of use, renovation, or change in energy status, it must comply with the applicable requirements of Schedule One, including energy efficiency and thermal performance standards. Major renovation or replacement of over 50% of a thermal element’s surface area must meet updated performance criteria. Additionally, for energy status changes, compliance with Part L requirements is necessary, and in the case of multiple dwellings, SAP procedures may be used to assess overall energy use and CO₂ emissions.

Section Twelve: For existing buildings over 1,000 m², any work involving extensions, new fixed building services, or increases in service capacity must ensure compliance with Part L requirements, provided it is technically, functionally, and economically feasible. This rule does not apply to renewable energy installations. Further technical guidance is detailed in Volume Two of the Approved Document.

In the next episode, we will move to Approved Document L: Conservation of Fuel and Power, Volume 2 — Buildings Other Than Dwellings.

I hope you enjoyed this episode and that the considerations of Approved Document L: Conservation of Fuel and Power, Volume One — Dwellings are clear for you now. If you have any questions, reach out to me on LinkedIn or send me an email — I'm more than happy to help you out.

At Bytnar Designs, we deal with planning, designing, and managing your projects, and we are always glad to facilitate a free initial consultation to steer you in the right direction. Visit www.bytnar.co.uk — and get in touch—whether your question is, “Can you help me with my project?” or just “What should I do?”, we’ll give you honest, no-obligation advice.

At Bytnar, we help our clients design and execute their dream homes or property investments.If your building is falling apart, we can also help investigate the reasons and provide you with the right strategy, design, and specifications for repair.

Thank you again for listening in. Please share your thoughts—I'm waiting for you on LinkedIn and want to hear from you.

See you next week.Bytnar Designs the World Around You.

Toodloo! 👋

---

Piotr Bytnar BEng (Hons) MSc CEng MIStructE

Chartered Structural Engineer who deals with the Architecture of buildings. His Master's Studies led him to an in-depth understanding of risk and contract arrangements in construction as well as specialist knowledge in soil mechanics.

He and his team help homeowners and property developers to design and deliver construction projects reducing waste in time and the cost. He believes that the construction project is an iterative process that can be well managed and it is best managed if all the aspects of the project definition and management are dealt with in-house or coordinated by one organisation. His team works to all stages of RIBA and ISTRUCTE stages of work and enables contractors to deliver projects on-site providing risk evaluations, methodologies for execution of works and temporary works designs.

---