BYTNAR - TALKS
EPISODE 031 - APPROVED DOCUMENT O - OVERHEATING
This episode is for people who want to know more about Approved Document Part O – Overheating.
You should like this episode if you ask yourself questions like:
What is the Approved Document O and what does it cover regarding overheating prevention?
How does the Simplified Method help reduce overheating in new residential buildings?
What strategies are recommended in the Simplified Method for managing heat and solar gain?
What is Dynamic Thermal Modelling and how does it apply to building design for overheating prevention?
When should additional considerations be taken into account for overheating mitigation in buildings?
What factors should be considered beyond just heat management in overheating prevention strategies?
What information must building owners receive regarding overheating mitigation strategies?
How can building occupants keep cool during hot weather according to the Home User Guide?
Are there specific guidelines for communal spaces and mixed-use areas regarding overheating prevention?
This is Bytnar Talks the Engineer Takes on Construction Episode 31 hi I'm Piotr Bytnar each day I help my clients plan and design building projects through Bytnar Limited a Consulting Charter 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 buddying software developer. so you can rest assured that I will strive to talk about the 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 approve document o overheating [Music] hi guys and welcome to bit nut talks your favorite podcast on all matters of architecture engineering and construction it is Sunday the 20th of October 20124 and I'm here back with you with the 31st episode and in information on approved document o overheating I am super happy to be back with you to deliver on yet another approved document we are slowly getting to the end of the whole lot as we do at the end of the year I cannot wait to start changing the topics and start delivering on things perhaps more lively than the dry reading of the legislation and the guidance that follows it fortun or unfortunately the industry is full of legislation and standards so it will be often inevitable to get back to it but I'm looking forward to deliv ing on topics that are more Universal anyway the last episode treated on the accessibility of buildings ordered than dwellings let's get quickly through the recap and see what was covered last week in the last episode I talked about the first volume of the approved document second volume of our approved document M access to and use of buildings dealing with buildings or than dwellings section zero in the document brings us the over view of accessibility requirements it tells us that this document highlights the importance of ensuring that buildings are accessible to all individuals regardless of age gender or disability by meeting functional performance criteria it applies to both new constructions and existing buildings undergoing significant changes with a focus on compliance with the equity act 2010 to eliminate eliminate physical barriers for those that use it that are external or people that actually operate the building section one deals with access to buildings this section provides detailed requirements for creating accessible routes from side boundaries or parking areas to building entrances ensuring they are firm level sleep resistant and free from hazards specific dimensions for Pathways ramps and other access features are outlined with references to best practices for accessibility such as inclusive Mobility guide in section two access into buildings we are shown how entrances how the consider consideration of entrances should be should be met they must be safe and easy to use for everyone including people with disabilities with clear signage level thresholds and appropri door widths both manual and power doors must be user friendly and safe an alternative accessible entrances must be available for revolving doors with clear visibility for glass doors to prevent accidents section three deals with horizontal and vertical circulations in buildings this section focuses on ensuring smooth movement for all users particularly wheelchair users Within nonre residential buildings in it outlines guidelines for entrance holes corridors stairs and lifts emphasizing space requirements proper layout and the need for compliance with safety standards for seamless navigation within the building in section four facilities in buildings yeah you guessed it we deal with facilities like sitting refreshment counters sleeping accommodations or must be accessible to everyone including wheelchair users specific guidelines ensure that wheelchair users can access public spaces Electro halls and Sport venues without segregation and the section covers the provision of accessible controls switches and communication AIDS like induction Loops section five deals with sanitary accommodation in buildings where sanitary facilities including toilets and showers must be accessible spacious and equipped with support rails alarms and easy to use controls special guidelines cover wheelchair accessible unisex toilets as well as ensuring that separate sex facilities are also suitable for disabled users with adequate space and safety features in this episode I will move to approv document o overheating so without further Ado let's dive straight into this [Music] in this episode I will talk about the statutory guidance contained within the approved document o overheating the document covers the requirements of part o and Regulation 40b and it is contained within four sections section 0 to three deals with overheating and section four covers the necessity to provide information to to the building user so let's get into the nitty-gritty of this approved document all right guys starting with the text of the legislation I will do both parts here so the requirement o and regulation 40b coming straight AA part o overheating overheating mitigation requirement 01 paragraph one reasonable provision must be made in respect of a dwelling institution or any other building containing one or more rooms for residential purposes other than a room in a hotel residences to a limit unwanted solar gains in summer B provide an adequate means to remove heat from the indoor environment and paragraph two in meeting the obligations in paragraph 1 a account must be taken of the safety of any occupant and their reasonable enjoyment of their residents and B mechanical cooling may only be used where insufficient heat is capable of being removed from the indoor environment without it and off to regulation 40b providing information information about overheating requirement 40b paragraph 1 this regulation applies to building work in respect of building where part all of schedule one applies where part o of schedule one imposes a requirement in relation to building work and paragraph two the person carrying out the work must not later than 5 days after the work has been completed give sufficient information to the owner about the provision made in accordance with part o so that the systems in place further to part o can be operated in such a manner as to protect against overheating that went quickly didn't it this approved document is pretty straightforward so section o as ever gives us an introduction to the document this requirement applies to new residential buildings only so dwelling houses and flats institutional overnight accommodation like schools care homes or any living accommodation for that matter except hotels shared communal rooms or spaces for more than one residential unit also fall under under the consideration of this requirement as the spaces that are particularly or sorry partially used for work some of these live work units may need an agreement with the building control on how to treat it as there is no particular definition to what is considered a substantial proportion of the building and that's how we are supposed to judge about it so bear that in mind in other clearly mixed you scenarios the requirement only applies to the res IAL part and its Corridor or otherwise the access route as is the case with other approved documents we may show competence in other ways than that's suggested but agreement on that may need to be made before the building is executed some interaction with other requirements are noted here like with Part B where additional addition of Escape Windows may lead to overheat or the amount of window opening for overheating will be higher than the PGE ventilation requirements of power F or the additional ventilation May influence the use of combustion appliances that's part J part L on the other hand may work in opposition when solar gain is considered for heating gains in Winter the same may cause overheating in summer naturally for controls this should be accessible in line with part K and M requirements but part o will have higher provision for the protection of falling from openings than that of part K the security of the doors and windows should also be considered in line with part C requirements in the gists requirement Out treats on the reduction of high indoor temperature occurrences and that should be done by limited unwanted solar gains in summer and providing adequate means of removing excess heat from the indoor environment and it is all about the Health and Welfare not necessarily the comfort of the occupants the Secretary of State identifies two methods for achieving compliance called simplified method and dynamic thermom modeling and these are being dealt with in the next two sections in section one we treat about simplified method a checklist is available in appendix B that takes us through all the building control approver wants to see it's three parts with part one stating the building and design as details part two indicates side details like location and building category chosen this designed overheating mitigation strategies like maximum area of glazing maximum area of glazing in the most glazed room shading strategy total minimum free area bedroom minimum free area and Des designers declarations then the part three is for the Builder and the building control body inspector to complete to confirm that the building followed the strategy so first we categorize the building where it is located and whether it has a cross ventilation or not for the lo location buildings in England the risk will be generally considered moderate apart from the highly dense urban areas of London where the risk is considered high there is a map and list of postc within the appendix C that we can refer ourselves to cross ventilated houses or flats will be such that have openings on opposite sides and each part of the building should be treated separately in that regard once we know these two parameters we choose how we will mitigate the gain and how we will remove the excess heat to limit the solo gain we follow the consideration of the Maxx maum glazing areas in the facade glazed the most and for that we have handy tables with prescription percentages of the floor area for glazing for the cross ventilated units we think between 22 and 37% off floor area of the room maximum for the most glazed room in the building and between 11 to 18% for the maximum area of glazing of the floor area anyway have a look at the tables the units without cross ventilation will obviously have smaller limits in addition the maximum glazing areas in the high risk locations between Northeast and Northwest via the South should either have external shutters with ventilation options or glazing with maximum G value of 0.4 and minimum light transmittance of 0.7 or have over hangs with 50° altitude cut off on due self facing facades only removing the excess heit is by the means of opening the windows wide and slightly different size of the free area of the opening will be required depending if the building is in high or low risk type of situation the percentage is given in minimums of the room floor area and glazing area so for bedrooms this will be 13 and 4% of floor area and otherwise 6% to 12% of floor area in between 55 to 95% of the glazing area we can calculate the equivalent area but Following bs1 13141 part one or following appendix D it is generally consider that this expectation will exceed that of purge ventilation of document F we need need to mind though that buildings using distributed heat and hot water systems may have extra heat load coming from the piping so the simplified method will not be suitable here this leads us to section two which covers Dynamic thermal modeling and this methodology is suitable for all residential buildings and may lead to more flexibility especially when the building is all airtight and with higher levels of insulation when we want to use the particular location of the building in consideration or when the buildings are highly shaded the dyamic thermal modeling method should follow the methodology of cib's tm59 publication but to be limited to choices as described in this document and report on this following the checklist as previously with simplified method the limiting parameters are for the day used between hours for the day use between hours 8:00 a.m. to 11:00 p.m. if the indoor temperature goes above 22° C the window should start to open and reach full opening by the 26° indoors and vice versa for the night time between 11: p.m. to 800 a.m. the opening should be modeled as fully open when on the first floor or above and not easily accessible and the internal temperature exceeds 23° when the ground floor or easily accessible rooms are unoccupied they should be modeled as open during the day if there are otherwise secured and should be considered closed at night an entrance door should be considered and closed at all times the following strategies should also be considered limited solar gain by the use of fixed shading devices like shutters external blinds overhangs and awnings consider glazing design taken in consideration its size orientation G value depth of the window reveal also think about building design in general with its different elements like balconies articulations and features as well as shading provided by other power permanent buildings structures or Landscaping foliage and internal blinds are excluded from the con consideration but for more guidance on what to include and what is effective take a look into into bre BR 364 solar shading of buildings publication removing excess heat is done typically by opening Windows ventilation louvers in external walls mechanical ventilation or cooling systems the preferred methods are naturally achieved by passive methods and it will need to be demonstrated to the building control that such methods are insufficient before specifying The Mechanical Solutions section three it may be the case that for some reasons the simplified method of achieving appropriate level of heat mitigation is not possible and these reasons can be varied for example we should consider noise levels at night as this may preclude us from the use of openable Windows generally if the average noise is over 40 DB over 8 hours between 11:00 p.m. and 7:00 a.m. or at least 10 times a night higher than 55 DB in between the same hours we will need to be a little bit more clever than just using Windows for our heat dissipation strategy when external air is not suitable for use in the strategy we may need to ventilate and filter the air security should be achieved by either not providing overnight opening Windows in position of easy access or protecting them with Grill grillages railings Lou shutters the protection from falling tells us to protect open Windows when needed if the window can open by 100 mm it can be considered a part of the strategy but then if they open outwards the handles cannot be further than 650 mm away from the inside face of the wall when the window is at its maximum opening position Guardian Heights will depend if the drop is higher than 600 mm or not for the Lesser drop height we are referenced to document K but for higher drop we need to provide guarding up to 1.1 M height and the guarding should not be easily easily climbable for large openings the guarding may as well be fixed or be formed of shutters with childproof locks we also need to consider the protection from entrapment as is the case in Doc K the 100 mm spare limit prevails when we think about babies heads getting stuck but with we we should also think about thingers so if there is an 8 mm Gap well then it should be at least 25 mm and it should not taper so to un trop a finger at any point and looped cords must be fitted with child safety devices now going off to section four which covers the provision of information it is all about giving the information to the owner of the new building so that they can use the building effectively so what do we need to provide well it is a non-technical instruction manual on how to use the overheating mitigation strategy and the maintenance requirements so the overall overheating mitigation strategy needs to be included the location of all elements of the mitigation strategy instruction how to use the these elements the time of day when they use what and when in terms of Seasons it should be used at manufacturers contact details the location of controls and instruction for setting of controls the location of senses and how to recal recalibrate them and cleaning and maintenance instructions this should be included within the home user guide intersection called staying cool in hot weather we are also reminded that the systems may be shared with other considerations like these for ventilation or conservation of fuel and power and this should be treated on separately within the [Music] manual so this is it folks the approved document o overheating let's sum it up section by section section zero introduction this section outlines the scope of the document which applies to new residential buildings including dwelling houses floods and institutional accommodations like Care Homes and schools IT addresses communal spaces and live work units requiring agreements with building control or mixed use situations the section highlights interactions with other requirements such as Part B FJ l k m and Q emphasizing the balance between safety ventilation and overheating prevention section one deals with simplified method and the simplified method provides a checklist in appendix B for mitigating over heating in residential buildings it categorizes buildings by location and ventilation type with high risk areas identified for special treatment strategies include limiting solar gain through glazing restriction and shading and removing excess heat via window openings the method is straightforward but not suitable for buildings with high heat loads from distributed systems section two Dynamic thermal modeling this section introduces the concept of damic thermal modeling offering more flexibility especially for airtight or well insulated buildings it follows the cibs cibs tm59 method ology and allows for detailed consideration of the building's location and shading strategies focus on solar gain limitation and excess heat removal favoring passive measures like shading and natural ventilations with mechanical systems as a last resort section three deals with additional considerations like in the case of simplified method Is it feasible factors Such Noise unsuitable external air security and F protection need to be considered this includes using secure ventilation options protecting open windows from Fallen Hazard and ensuring child safety by preventing ENT trapment in window mechanisms special attention is required for buildings in noisy or highrisk areas section four deals with provision of information for the building owner and owners must be provided with a non-technical manual outlining the overheating mitigation strategy this includes details on how to operate and maintain mitigation elements timing for their use and contact information to manufacturers it should be part of the home user guide covering how to stay cool during hot weather alongside other systems for ventilation and energy conservation in the next episode I will move to approve document p electrical [Music] safety I hope you enjoyed this episode and that the considerations of the approved document o overheating are a bit clearer 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 in bitna we deal with planning designing and managing of your projects and we are always glad to facilitate a free initial consultation to steer you in the right direction visit www.b TN do.uk that's www.but now.co and reach out to us whether your question is if we can help you with your project or what should I do we will be able to give you a piece of non obligatory advice at bitna we help our clients design and execute their dream homes or Investments if your building is falling apart we can also help investigate the reasons behind it and to provide you with an appropriate strategy design and specifications for the repair thank you again for listening please voice up your opinions I'm waiting for you on LinkedIn and I 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.
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