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  • HPH279 : A beginner’s guide to building terminology – with Lee Fordham from Architype

    HPH279 : A beginner’s guide to building terminology – with Lee Fordham from Architype

    Lee Fordham from Architype simplifies some of the terminology you might come across if you’re thinking about doing a sustainable self build.

    Interview with Lee Fordham

    Shortly after qualifying as an architect in 2004, Lee spent time travelling and working for architecture practices in New Zealand and Australia. When he returned to the UK he decided to pursue his passion for sustainable design and started working at Architype, one of the UK’s leading sustainable architects, where he is now an Associate Director.

    A beginner’s guide to terminology

    For those that are just setting out in their self build journey there can be an overwhelming array of technical terminology used that can be baffling to anyone outside of the industry. Lee takes us through some of the common terms that you might come across in a sustainable self build.

    Passivhaus / Passive House

    Passivhaus (Passive House in the United States) is a building standard that was developed in Germany around 30 years ago. Using physics, the aim is to reduce the performance gap between how the building is designed to perform, and how it actually performs.

    The aim is to make the building more comfortable for the occupants and reduce how much energy the building uses, which is done with a better quality of build.

    Liz and Mike Hill’s Passivhaus – designed by Architype

    The experts will use the Passivhaus Planning Package (which you’ll hear referred to as PHPP), which essentially is a very complicated spreadsheet of data that allows them to design a building that will meet the Passivhaus criteria. The contractor will use that information to construct the building, and a certifier will guarantee the work and certify it if it meets the required standard.

    Passivhaus plaque

    MVHR

    You’ll commonly hear a Mechanical Ventilation Heat Recovery system referred to as an MVHR. They’re most likely to be used in Passivhaus buildings, but not exclusively. It is a ventilation system which extracts the used air from inside a building. It takes the heat from that air and mixes it with fresh air which is being brought into the building from outside, to provide every room with fresh, pre-warmed air.

    The air is filtered coming into the building, and different filters can be used according to whatever is in the external air in that area.

    A key benefit over natural ventilation is the element of control over any given space, ie removing moisture from bathrooms etc.

    An MVHR for a domestic dwelling is roughly the size of a combi-boiler and will need to be incorporated into the building’s design.

    MVHR unit at Landsdowne Drive Passivhaus – Green Building Store

    Foundations / Footings

    These will usually be designed by a structural engineer and are what sit under the building to evenly transfer the weight of the building to the earth. The type you use might be dependent on what your ground conditions are like, but some examples are pile foundations, deep strip foundations and raft foundations.

    U-value

    A complicated one to explain, but essentially it’s a way of measuring how thermally conductive a component or a series of components (like a piece of glass, wall or roof) is. It is the rate at which heat travels through. The lower the U-value, the better it is.

    The aim is to have fairly consistent U-values across all the components in a building. Having just one element that isn’t consistent could act as a magnet for moisture and potentially damage the structure. This can partly be achieved by better insulation, triple-glazed windows etc.

    The U-values form part of the data that feeds into the PHPP system.

    Airtightness

    At a very basic level, this is about eliminating drafts in a building. It’s relatively easy to achieve but needs to be thought about at the design stage. At Architype they denote the airtightness layer on their detailed drawings using a red line, which shows the contractors where to take particular care in the construction so as not to damage it.

    To meet building regulations, when the building is finished an air test will be carried out. The building has a giant fan attached to it and is either positively pressured, ie blowing air in, or negatively pressured, ie extracting air. The rate at which the air leaks gives you your air test result. It is a measure in pascals of the pressure of an internal area. Building regs require you to get a result of 10 or less.

    The method in a Passivhaus building is slightly different. This takes an average reading from the building being both positively and negatively pressured, to give an n50 value which is how many volumes of air changes there are in an hour. The Passivhaus requirement is that it should be less than 0.6, so significantly better than building regulations.

    Build system / construction method

    This is a way of describing what method you are going to use to construct your building. Examples include timber frame, masonry, brick and block, insulated concrete formwork (ICF), pre-cast concrete, in-situ concrete, and cross-laminated timber.

    Pre-fabrication

    Pre-fabrication is where components, or indeed whole buildings, are made off-site. This could be from wall panels, to timber frames, to bathrooms that are fully plumbed and tiled, to entire houses.

    MAKAR production facility

    You can even go to the factories and choose your handles, paint finishes, floor finishes etc. When they reach the site they are connected together. The advantages of building the elements off-site is it can be quicker, they’re not subject to delays or damage from the weather, and often it can result in better quality and working better when brought to site.

    Huf Haus

    Zero carbon

    Lee says that this is a difficult one to explain as there are many different interpretations of what it means.

    Generally it refers to off-setting the energy use in a building. So the better your building is, ie a Passivhaus, the less carbon you have to off-set because you’re not using as much energy.

    Looking deeper into it, some people will be referring to zero carbon in use, which is the energy that is used starting from the point of when it’s been built, through to its end of life.

    But there’s also embodied or sequestered carbon, which takes into account everything to do with the design and construction of the building, together with the in-use energy and sometimes through to the demolition. This is more complicated to account for, although there are tools which can help explain for instance, how much energy is used in getting a tree from Germany to the UK to use in a timber frame.

    Custom build

    Whereas self build has many decisions for you to make, whether or not you’re doing it in the purest sense of building it yourself, or whether you’re commissioning someone to carry that out for you, custom build can take some of those decisions away from you. There will be an offering from the custom build company, but with options for you to customise it. That could be in terms of the style of the house, the layout or the finishes. It might not be as individual as you would get with a self build, but it can take away a lot of the headaches!

    Potton Homes design

    Solar shading / brise soleil

    Effectively the same thing, brise soleil or solar shading would be used on the south facing side of a building to limit the sun coming in during the summer months when you don’t want the building to overheat, but allowing it to come in during the winter when the heat is required. Generally it would be a horizontal component that sits over the south facing glazing, whether that be a roof overhang, external canopy or series of louvres.

    External louvres – Charlie Luxton Design
    Wimbish Passivhaus Scheme – Parsons & Whittley
    Ditchingham Passivhaus Scheme – Parsons & Whittley

    On an east or west elevation you would usually have a vertical component, and that’s just to do with the angle of the sun at certain times of day and certain times of year. Windows on the east and west elevation can be harder for dealing with glare and overheating issues.

    Lee says the ideal situation is to have the building facing south where the solar gains can be controlled more easily.

    Design team

    The core members of a design team are likely to include: an architect, structural engineer, civil engineer, mechanical and electrical (M&E) engineer, and possibly a project manager.

    Beyond that, depending on your site and your level of involvement and interests, you might also have: landscape architect, ecologist, arboriculturist, quantity surveyor, Passivhaus designer etc.

    Renewables

    Renewables refers to technology that generates energy. This could be photovoltaics, wind turbines, hydro power etc.

    Air source and ground source heat pumps

    An air source heat pump takes energy from the temperature in the air. Any air above zero degrees has energy in it and this can be taken and transferred into heat or hot water for your house. Similar in size to a washing machine, they’re put on the outside of a building.

    The ground source heat pump works in much the same way but will take the energy from the ground. They have pipes which can either be spread horizontally in the ground which will require a lot of space, or as a vertical spread of pipes, which need less space but are a lot more expensive.

    Plans, elevations, sections and details

    These are examples of the different types of design drawings, created by Parsons and Whittley for Ben Adam-Smith’s house:

    Plan – This is an aerial view, looking down onto the building. You can have different plans to show each floor of the building, but they can show the roof, doors, walls and windows, together with the internal layout.

    Elevation – An elevation is a drawing of what the outsides of the building look like from where you’re standing. A south elevation for example would be the side of the building that is facing towards the south.

    Section – This is like slicing down through a building to show what’s inside. It will show the components of the walls, floors, roof etc.

    Details – By taking a section drawing and zooming in you will create a detail. They can be various scales, such as 1:2 or 1:10, and are an in-depth analysis and instruction for the contractor showing how to construct that part of the building. It would show them where the airtightness line is, where the insulation is, and how wide cavities would need to be.

    Soft landings and performance monitoring

    A soft landing is about making sure that once the building has been constructed, that the operator of that building knows how to use it. Obviously if you’ve built it yourself then this wouldn’t be necessary, but if you’ve largely commissioned other people to complete the project then you should have someone tell you how it all works.

    Performance monitoring can take place throughout the build process but in particular Lee refers to monitoring once the building is complete. This uses sensors to check on things like the internal temperature, humidity and CO2 levels, to make sure the building is performing as it was designed to do.

    Tender

    The way you tender will depend on what kind of contract you will have, but essentially a tender is a set of information that is put out to someone for a response. They will price up the aspects on the tender and return it with their figure and requested documentation. It can be a tender for a design team or for a contractor. The returned tender documents are then scored and weighted according to whatever your priorities might be. For some that might be 80% of the marks will be based on how competitive the price is, but for others they might weight it more heavily in favour of quality and not necessarily who is the cheapest.

    A key thing is to make sure the information and drawings you are sending out are as comprehensive as possible. That way it can be priced accurately for what you will be needing. Without that detail they will be adding an element of price risk to their response which will invariably make it much more expensive.

    Window parts

    • Sill – The ledge at the bottom of the frame.
    • Head – The top of a window where it meets the wall. It can be internal or external.
    • Jamb – The side of the window
    • Reveal – The part next to the jamb. Can be internal (usually plasterboard) or external (usually timber or brick). If the reveals are set very deep into the thickness of a wall they can provide some shading to the window
    • Mullions and transoms – Found on traditional Victorian style windows, the mullions are the vertical bar in the middle of the window, and the transoms are the horizontal bar.

    Roof parts

    • Trusses – The pieces, usually made of wood, that actually make the roof structure
    • Joists – A horizontal structural element that supports the floor and/or ceiling
    • Eaves – The part of the roof that overhangs the wall. Usually if it’s a sloping roof it would be the part which overhangs the gutter
    • Soffits – Underneath the eaves, the soffits are the horizontal section that you can see
    • Ridge – The point right at the top of the roof, usually where two pitches come together
    • Verge – The part at the side of the house. Usually there would be a bargeboard or piece of wood that goes down the side
    • Parapet – Usually a piece of wall that protrudes up above a flat roof
    Roof trusses
    Roof joists

    Find out more

    Visit the website of Architype

    Follow Architype on Twitter

    Transcript

    Download a transcript of the interview with Lee Fordham.

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    If you’re new to self build and looking for more information, then be sure to check out The Hub. It’s full of great resources, video diaries and support from a community of like-minded self-builders.

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  • HPH193 : Should you specify uPVC windows? – with Simon Corbey from ASBP

    HPH193 : Should you specify uPVC windows? – with Simon Corbey from ASBP

    Simon Corbey from ASBP shares some of his research into the costs and life cycle of plastic windows and suggests some considerations for self-builders.

    Interview with Simon Corbey

    Simon Corbey worked as a chartered surveyor in the ‘90s, and went on to become a specialist in natural paints for London’s first eco builders’ merchant, Construction Resources. He has also worked for BioRegional, the Sustainable Development Foundation, the Good Homes Alliance and the Alliance for Sustainable Building Products (ASBP). Last time we spoke to Simon, he talked to us about healthy building products.

    We should question the chemicals in uPVC

    Simon Corbey has been working on behalf of the ASBP to compare plastic and timber windows. Consumers tend to be more concerned with how windows will look and last than where plastic comes from and the issues around it. Simon remarks that plastic windows are manufactured widely in the UK, but these impacts are not really considered, adding, “I do think that there’s an opportunity for the UK to develop their building physics and approaches to making windows.”

    Simon notes that plastic windows appeal, as they are generally cheaper and available in a range of styles. He describes the marketing as aggressive, adding, “It’s well funded, of course. It’s the petrochemical industry.” Plastic windows contain a range of chemicals but no research has suggested a negative effect on indoor air quality. The window itself may be benign, but Simon has also been researching product manufacture and life cycle.

    Manufacturing chlorine is hugely energy intensive

    Simon explains that uPVC (unplasticized polyvinyl chloride) contains chlorine. Used in swimming pools and our water supply, it’s common enough to not raise concern. However, he explains that its manufacture has an incredible impact on the environment.

    Simon estimates that producing 80% of the UK’s chlorine uses more electricity than Liverpool. Production of PVC in Europe in 2015 used 8.6 million tonnes of chlorine. “So it’s hugely energy intensive,” says Simon, adding, “From a life cycle analysis it’s a terrible, terrible thing.”

    Simon’s research shows the hidden costs of uPVC windows

    Simon has further researched Ineos, who produce most of the UK’s chlorine. Describing it as “a very murky world,” he says he feels motivated to bring this to people’s attention. The site of the Ineos plant in Cheshire is of particular concern. Simon describes how Ineos were caught dumping mercury into the Manchester Ship Canal in 2014 and the land contains a dump once used to “make everything from nuclear weapons to World War II stuff”.

    Previously owned by ICI, the dump was linked to toxic chemical leaching and reports of ill health in the early 2000s. Today, explains Simon, if you look at the Land Registry, this dump apparently has no owner. “There is a completely toxic dump just there which the council don’t own,” he says. “Ineos have somehow redrawn the lines of their site and conveniently they don’t own it any longer.”

    Timber windows struggle to compete on price and marketing

    Despite their significant environmental price, plastic windows remain cost effective for manufacturers. The price of oil and gas is still low, making the raw materials cheap. The process of gathering timber, processing, sawing and milling it is quite energy intensive in comparison and the end product is heavier to transport. All of this adds to cost.

    Simon further points out that the UK timber industry is quite fragmented, containing many different disparate interests. Conversely the plastics industry markets products with “one voice”, typified by slick campaigns, such as that for Everest windows. Moreover, Simon describes it as quite litigious, recalling a threat of court action when his former employer persuaded a Scottish Housing Association to cancel their order for plastic windows.

    Plastic windows may not outlast timber

    There is a perception that timber windows will rot, requiring repeated maintenance, while plastic is assumed to be tougher. Simon questions these preconceptions. While acknowledging that timber windows have a finite life cycle he points out that plastic windows are prone to yellowing after a while. Simon himself has 120-year-old timber windows, which are “going strong”. “They’re a bit leaky,” he says, “but they’re okay as far as I’m concerned.”

    Other options for window materials do exist. Simon recommends considering factors such as product life cycle and building location. Aluminium is very durable but highly energy intensive; composite timber and aluminium windows are one alternative.

    The quality of UK timber windows is improving

    Windows are an essential part of the building fabric’s performance. With improvements in building science, double glazed and triple glazed windows are appropriate for new builds and both plastic and timber windows can achieve Passivhaus Trust certification.

    Where good indoor air quality is maintained by natural ventilation, windows must function well, being easy to open and clean. There have been some issues of quality with some timber windows but Simon sees this improving, following the standard of European and Scandinavian manufacturers.

    Recycling plastic windows involves additional expense, chemicals and risks

    The Scottish Civic Trust suggests that the recycling rate for windows might be 3% and according to the Green Guide, BRE suggest that the UK average is about 15%. However, Simon suggests the many issues with recycling, such as the chemicals and risks involved, make that figure optimistic.

    The formulation of plastic has changed quite a lot since the ‘60s and the industry has made great attempts to clean itself up. Substances considered by REACH to be of very high concern, such as lead and cadmium, are being phased out although tiny quantities are still allowed.

    Plastic is worse than wooden windows in a fire

    Simon believes that toxicity is a huge issue. He confirms that plastic windows pose a greater risk than wooden ones in the event of a fire and believes that more research is needed. However, currently all the testing institutes are very busy “as a result of Grenfell”.

    Simon notes that in the USA, The Healthy Building Network has liaised with the Fire & Safety community to argue for a complete halt to use of plastic products. Likewise, the ASBP has initiated contact with Kent Fire and Rescue and the London Fire Brigade. As Simon explains, “there is some research underway but it’s early doors, I would suggest, this type of testing.”

    Industry and consumers are moving away from plastic

    Techniques and attitudes continue to change. Acetylated wood is an example where window science has improved. This process basically uses vinegar to extend the maintenance life of timber to over 60 years.

    Simon notes a growing interest in health and wellbeing, as well as a global campaign against plastics. He summarises, “I think at ASBP we’re trying to suggest that as a society we’ve just got to start using less plastic through and through, in all the things that we do and windows being one of those things.”

    Find out more

    Visit the website of the Alliance for Sustainable Building Products (ASBP)

    Follow the ASBP on Bluesky 

    Transcript

    Download a transcript of the interview with Simon Corbey

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  • HPH186 : Choosing windows for a Passivhaus home – function versus aesthetics

    HPH186 : Choosing windows for a Passivhaus home – function versus aesthetics

    Ben and Kay Adam-Smith have a difference in opinion over which windows to specify for their new build Passivhaus home. While Ben is keen to minimise mullions, transoms and window frames, Kay believes this takes away from the aesthetics of the building.

    A visualisation of Ben and Kay’s house

    Today’s episode is really a short story about aesthetics. Life would be boring if we all liked the same thing. However, what happens when you’re working with your other half on a self build and you strongly disagree about something? How do you move on? Well we haven’t answered that one yet, but we can share the disagreement and let you know what happens over the course of time!

    I (Ben) also feel like I might have said what my wife is saying a few years ago. I believe I’ve grown in my understanding since then and so now my opinion has changed.

     

    Mullions, transoms and window frames

    Firstly what are mullions and transoms? Well, they are the structural elements that divide up sections of a window. Mullions are vertical while transoms are horizontal.

    There’s no denying that the use of mullions and transoms can make some beautiful windows (as in the stained glass window above, where it’s taken to an extreme).

    In the past it was just not possible to manufacture large single pieces of glass and so to achieve a big window, a number of small ones needed to be ‘stitched’ together.

     

    Large glazing is now possible

    Probably a window’s most important function is to provide that visibility from one side to the other.

    Windows without mullions and transoms therefore do a better job of connecting the inside to the outside (and obviously bring in more light).

    As we spend 90% of our time indoors, you could argue that the view out is more important than the aesthetic appearance of the window from the outside.

     

    Large single pane windows are still not the norm

    In a country where our period properties make up a large proportion of the housing we live in today, it is hardly surprising that we gravitate towards their features.

    That’s perhaps why Kay would like two of three ‘lights’ (subdivisions) in each window.

    She also thinks that a lot of houses that use large panes of glass just don’t look right; they look like they need to be sub-divided.

     

    Reducing the amount of glazing in a window affects its performance

    The frame is generally the weak point of the window.

    Chris Parsons of Parsons + Whittley says: “We want more glass and less frame in the way, because the more glass we have the better the performance of the window. When you start dividing them up with mullions and transoms, you now can’t insulate that part of the frame by wrapping anything around it.”

    How much glass is actually in a window?

     

    PHPP models the amount of glass and the amount of frame

    Even if a window has a good central pane U-value (a measure of how effective it is as an insulator), it is only referring to the glass. Therefore the Passive House Planning Package (PHPP) requires information on both the amount of glass and the amount of frame in every window. This is the only way to produce an accurate model of the thermal performance.

     

    The ease of opening and closing windows depends of their size

    While performance is important when creating a Passivhaus, it must also be balanced with practicality.

    When windows get too big, they take a bit more manoeuvring so this could become a valid reason for introducing different lights in certain windows.

     

    Aesthetics will always be a key driver in window choice

    There is no doubt that windows with mullions and transoms produce a pretty pattern on the window.

    It is also possible to get Passivhaus sash windows, for example. However, for new build, does it make sense to specify sash windows (given all the arguments above)?

    This is a choice you’ll have to make . . . and a choice we have to make on our build!

     

    Keep an open mind

    This can be a great attitude to anything in life and it’s just the same with architecture.

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  • HPH038 : What Type of Windows Do You Need in a Passivhaus? – with Bronwyn Barry from One Sky Homes

    HPH038 : What Type of Windows Do You Need in a Passivhaus? – with Bronwyn Barry from One Sky Homes

    Bronwyn Barry from One Sky Homes explains the evolution of windows and why modern windows are really pieces of equipment. She also shares what’s involved when it comes to choosing high performance windows for a project.

    BB Profile Pic_edited

     

    Interview with Bronwyn Barry

    Bronwyn Barry is originally from South Africa but she studied architecture in America and never left!

    Her passion is for integrating good design with comfort and performance. When Bronwyn discovered Passivhaus, she felt it had the whole package.

    Smart-Win

    The Smartwin window system

     

    Windows Have Become More Sophisticated Over Time

    A window traditionally has two functions. Firstly it lets in light or air, and secondly it allows the dweller to see outside (or vice versa).

    In a high performance building, the windows are likely to be the weakest link in the chain when the whole building envelope is considered. So how the windows are built and how they are designed into the envelope is critical to making the full package work. 

    stained-glass

     

    Historically Windows Have Even Told Stories!

    Early windows were just tiny openings in buildings with no glass. As glass became more available, windows even became a status symbol for the wealthy.

    Bronwyn talks about the glass tax in Ireland where people were taxed on the number of windows they had!

    Gothic cathedrals really pushed the boundaries of what windows were, using them to tell biblical stories. 

    Goethe Haus, Frankfurt

     

    Building Science is Nothing New

    Bronwyn reflects on a trip to Frankfurt in Germany where she visited the Goethe House. On the top floor are the original leaded glass single pane windows from the 1600s which have a channel at the base and weep holes to allow the interior condensation that would form to drain to the outside.

    Bronwyn found this fascinating that building science was being used to come up with solutions centuries ago.

     

    Domestic Markets for High Performance Windows are Growing

    When Ben asks whether a Passivhaus needs different windows to any other building, Bronwyn says not necessarily. However, the windows must be very carefully designed and selected, taking in account the climate, orientation of the building and the materials.

    The good news is that there’s more and more choice on the market. While imports (from countries such as Austria and Germany) have dominated Passivhaus projects in recent years, local producers have cottoned onto the growing market and have started producing appropriate windows and even customised products for their specific markets.

    window-cross-section

     

    Windows Need to Function Differently According to the Project

    There are variables to take into account such as the solar access of the site. The energy balance will change according to the size of the building. Taller buildings, multi-family units etc. will have large internal gains compared to relatively small gains on single family, detached residences.

    Bronwyn explains with an example of one of her recent projects which had no solar access: “I’ve recently done a retrofit where our windows weren’t net energy producers. What I mean by that is the overall energy gain from the solar gain of the windows was actually less than the amount of energy that gets lost out of the windows, just because they are a weak insulation component in your full envelope. That was in California, where we’ve got really great solar access and a relatively mild climate but this was a project that had a whole line of redwoods across the southern border of the property completely shading the house. So we really had to choose our windows that would give us lots of natural light, which people still always want no matter where you are on the planet, and wouldn’t lose too much heat and maintain a relatively comfortable interior temperature.”

     

    Aesthetics Tend to Come First When Choosing a Window

    In Bronwyn’s experience choosing windows for a project generally follows this sequence:

    1. Select the ones you like the look of
    2. Look at the performance data to see they are adequate
    3. Consider the price

    Another factor to bear in mind is what materials the windows are made from. Some people do not want any uPVC on their projects!

    one-sky-homes-house

     

    Glazing Selection has a Big Impact on Heat Gains

    The glass that is chosen to go in the frame has a huge influence on how much heat gain there will be from that window. Again, this is due to a combination of factors.

    For example, quite often there are double pane or triple pane. There are a variety of films and coatings that can be applied to the glass too. Different gas fills can also go in between the panes, adding an extra layer of insulation.

     

    Do Gas Fills Leak Out Over Time?

    Ben raises the concern that these gas fills in the windows may not last and Bronwyn responds that in a recent study of a 10-year old window it was found that only a very small amount of the gas had escaped.

    There is currently debate that at high altitudes this could be more of a problem but even then there are workarounds.

    Bronwyn says: “If your glazing panel already has very poor performing spaces, so if they’re aluminium spaces holding the two panes apart that’s already probably a worse thermal bridge kind of heat loss opportunity than no gas in the window. And if your frame is a really poorly insulated frame that’s another bigger opportunity for worse heat loss. Then if the installation, how the window’s installed within the wall opening, if that has all sorts of metal pans that go from the inside to the exterior and big air leaks there again is another bigger offender.”

    rough-opening-framing

    Rough opening framing with air-sealing tape

     

    Everybody in the Chain of Custody has to do a Good Job 

    It is not a case of just buying a really high performance window and the job is done, because if it is put in a sub-optimum position in the wall or is not sealed properly to the building fabric, the overall performance will be diminished. So it is very much a team effort. Good communication and a little education can go a long way.

    As Passivhaus requires a blower door test it quickly reveals any poor workmanship, both in the production of the window and the installation.

    Solar Gains Need to be Carefully Controlled

    With the opportunity for windows to be great solar gain mechanisms they essentially become the heating system for these buildings. However, if this is not controlled carefully it will become an over-heater for a building which is also not desirable. 

    This was Bronwyn’s childhood experience in South Africa, where overheating and being uncomfortable from excessive heat was more the issue rather than lack of heat.

    So being able to shade the windows carefully and control the solar gain is just as critical as the window design and where they are located in the building envelope.

    Exterior-operable-shades-(berkley) Exterior operable shades in Berkeley, CA

     

    Your Shading Mechanism Should be a Long Term Proposition

    There are various shading mechanisms that can be used on a project such as an eaves overhang and brise soleil to exterior louvered blinds or a neighbouring building. Even trees can be used as part of your strategy. The important point is that it is a lasting solution.

    On high rise buildings it can actually be a coating on the glass itself that modulates the solar gain.

    Balance-Project

    Balance Project, New Mexico (Image courtesy Jonah Stanford)

     

    The Importance of the Window Frame is Often Over-Looked

    While architects and energy modellers can get engrossed in the glass specification the actual frame design itself can get skimmed over. The frame can make or break a high performance window.

    The glass can be replaced and most manufacturers provide a good selection of glass inserts but when it comes to the frame there are normally only a few options.

    That’s why Bronwyn’s top tip is to pay attention to how well a window is put together and also how it drains at the sill.

    OSH-Logo

     

     

     

     

    Transcript

    Download a transcript of the interview with Bronwyn Barry.

     

    Our Question for the Comments Section

    How have you chosen windows?

     

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