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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)

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    Transcript

    Download a transcript of the interview with Simon Corbey

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  • HPH096 : Is Natural Ventilation Fit for Purpose? – with Kara Rosemeier from Passive House Academy New Zealand

    HPH096 : Is Natural Ventilation Fit for Purpose? – with Kara Rosemeier from Passive House Academy New Zealand

    Kara Rosemeier from Passive House Academy New Zealand looks at why natural ventilation leads to little control of ventilation. She also shares why the Passivhaus approach is the logical step forwards.

     

    Kara-Rosemeier

    Interview with Kara Rosemeier

    After starting out in physiotherapy, Kara Rosemeier has spent most of her working life doing building physics. Currently she is the Director of the Passive House Academy New Zealand (no affiliation with the Irish Passive House Academy), a board member of the Passive House Institute New Zealand, a building physics consultant and a part-time lecturer at a university.

     

    The Term ‘Natural’ is Not Helpful When Describing Materials

    Kara believes that people’s desire to build with natural materials is misguided because there are problems defining the word natural.

    Kara admits that she may be particularly sensitive to the connotations of the term natural being non-heterosexual and fending off abuse such as ‘it’s not natural’.

    She says: “I question the division between natural with this connotation of healthy, good, desirable and unnatural meaning unhealthy, bad and unwanted.”

    Relating this to buildings there are many contradictions. Are buildings natural at all? Are people – and the things we do – natural? Kara concludes everything we do is natural.

     

    Natural Materials Can Emit Pollutants Too

    Kara recalls one house she monitored where the walls and floors were built from rammed earth. The homeowners had had a strong desire to build with natural materials yet the radon concentrations in this house were three times the maximum recommended by the WHO. Although Kara can’t say with certainty that the rammed earth was the culprit it is quite likely as radon is emitted from decaying materials and soil.

    Kara continues: “Wood, even completely without glues, is emitting formaldehyde. Not many people are aware of that. And timber dust is a potent carcinogen, so it’s not like nature tells you anything about whether a material is natural or whether a material is healthy.”

    Therefore our efforts should be on materials and construction that does not cause, or at least minimises, harm to people and fellow creatures. For this, information on production processes, ingredients and performance indicators is essential. The label natural does not substitute all this.

     

    Natural Ventilation Requires Constant Human Intervention

    Every hour we need about 30m³ of fresh air per person.

    If the building envelope is so leaky that no human intervention is necessary on a calm day it follows that the home will be horribly draughty on a windy day!

    Kara makes the analogy of this being like punching holes in your water pipes to occasionally have a shower. In other words, you wouldn’t do it.

    To provide adequate ventilation windows and doors must be opened at regular intervals.

    Again, the term natural falls down. Kara points out: “If we go with the – well in my view more or less meaningless – distinction that natural is free from human intervention, then natural ventilation is as unnatural as it gets. Free running is a much better term if you translate this to not being mechanically pressurised.”

     

    The Stack Effect is Not a Reliable Driver for Air Exchange

    Kara says that with a low rise building in a temperate climate, the stack effect is not a reliable driver for air exchange.

    It requires either a large temperature or height differential. Without mechanical help the wind is the main driver for air exchange, but wind is not steady.

    For the pressure that’s necessary to affect air exchange it also matters where on the façade the wind impacts.

    Kara says: “There’s at least a windward and leeward side of a building and you’ll have positive and negative pressures on parts of the façade as a result. But you don’t know where is what at any given time so whether opening a window will affect how many cubic metres of air exchange. Without constant pressure you don’t know what’s happening really.”

     

    Indoor Environments are Full of Pollutants

    It is not just the materials used in the construction of a house that contribute to the indoor environment. Anything that’s in your house – from furniture, decorations, utensils, cleaning products, etc. – will alter it.

    Kara recalls being given a reusable textile shopping bag at her local supermarket. Although it looked nice (and seemed natural!), she soon became aware of the terrible smell and had to leave it to air on her balcony for a month.

    Without monitoring equipment, it’s impossible for the homeowner to gauge indoor air quality. There could be particles such as nitrous dioxide or carbon monoxide in the air and nothing perceptible to the senses.

     

    Dilution is the Best Way to Control Indoor Air Quality

    While there are various approaches that would improve indoor air quality, such as extracting pollutants where they are emitted before they can spread through the house, ultimately dilution is the best solution.

    Kara says: “When you bring in about 30m³ of fresh air per person every hour then you can be reasonably certain that your contaminants are diluted to a level where they are not harmful.”

     

    A Tale of Two Living Rooms

    comparison of natural ventilation versus MVHR copy

     

    Monitoring of CO2 levels in 2 new 3-bedroom houses in Auckland over a week in winter. Both houses were inhabited by 4 people and a pet. Only the house with a balanced ventilation never exceeds the 1,000 ppm threshold, and shows a fairly consistent indoor air quality. This is in stark contrast to the free-running house, which relies on natural forces and someone opening the windows. CO2 readings here are strongly fluctuating, and far exceeding the recommended threshold at peaks.

    You Can Filter Incoming Air with a Pressurised Ventilation System

    One key benefit of building an airtight house and using a pressurised ventilation system is that the outdoor air can be filtered before it enters the house. So it won’t matter whether you live next to a busy road or in the middle of the countryside, you will still have fresh air.

    Passivhauses typically use an F7 filter, which is very fine and filters out almost everything that could be harmful.

     

    CO2 Concentrations Often Indicate the Presence of Other Pollutants

    The CO2 levels in a building are relatively easy to monitor. This is helpful for another reason as well because common indoor air contaminants correlate with these CO2 concentrations.

    *In some of Architype’s Passivhaus schools, the teachers report that their pupils are much more attentive in the afternoons compared to when they were in their old traditionally-built schools.

     

    Growing Plants Inside Doesn’t Necessarily Improve Air Quality

    Ben was interested whether growing plants inside houses does anything to the indoor air quality.

    While Kara says some research concludes that it helps with indoor air contaminants like volatile organic compounds or formaldehyde it will not help with CO2 levels (because plants will be emitting CO2 overnight).

     

    Using Natural Ventilation Will Not Lead to a Comfortable House

    Kara concludes that natural ventilation is not fit for purpose if your purpose is a comfortable and healthy indoor environment.

    It also makes little sense in terms of energy when heat or coolth is lost unnecessarily to the outside.

     

    Find Out More

    Passive House Academy New Zealand

    Follow the Passive House Academy New Zealand on Twitter

    Transcript

    Download a transcript of the interview with Kara Rosemeier.

     

    Film: Walter’s Way, London’s Self-Built Street

    If you have a spare 10 minutes this is well worth a watch. It’s a documentary short on architect Walter Segal, reflecting on his life and how he left his mark on self build in the UK.

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  • HPH034 : Balancing Environmental Design and Low Energy Design – with Wilf Meynell

    HPH034 : Balancing Environmental Design and Low Energy Design – with Wilf Meynell

    Architectural designer Wilf Meynell explains the concept of environmental design and why it is not the same thing as low energy design. He also shares how he has tried to balance these two approaches in one of his upcoming projects, Springfield House.

    Wilf-Meynell-photo

    Interview with Wilf Meynell

    Wilf Meynell studied architecture at Brighton University and then did a diploma at the University of East London. At the latter he was tutored by Sofie Pelsmakers, whom he credits for influencing him and developing his interest in environmental design.

    We Are Losing ‘Direct’ Control Over Our Indoor Environments

    Wilf was brought up in the countryside and has always had a good connection with his surroundings. However, he believes that as technology has improved and buildings have become better at monitoring themselves, occupants are starting to lose that link with the environment.

    Whereas opening a window or putting a log on a fire is very much instigated by the user, modern buildings maintain good comfort levels largely by themselves.

    Our Focus on Low Energy Design Could be at the Expense of Environmental Design

    While low energy design is a very good thing, Wilf thinks it should not be at the cost of environmental design. It is just as important to get the right specification of locally-sourced materials, to harness the full potential of the sun to provide energy, and to look at the prevailing winds and consider natural ventilation. Low energy design and proper environmental design need to come together in future constructions.

    Without a Strong Connection to the Environment We Lose Sight of What We’re Doing

    Taken to an extreme Wilf believes that focussing exclusively on low energy design could distance us from our environment. There could be knock-on effects with things like recycling and landfill, where we just see our environment as a body in which to store things we don’t want.

    Case Study: Springfield House

    Wilf uses one of his current projects to help explain how low energy design and environmental design can work together.

    Springfield-House-(visual-from-south)

    Visualisation of Springfield House

    The Site was Chosen to Get as Much from Nature as Possible

    Springfield House didn’t initially have a site but this proved quite good from an environmental design point of view because they were able to consider locations that could have as much from nature as possible. The plot they chose is south facing with well-managed woodland around it. Therefore there is a good source of timber for the construction and it can also provide fuel (waste timber not virgin timber) for the house once it’s built.

    Key environmental concepts such as this have helped push Springfield House towards Code for Sustainable Homes level six before even considering any green technologies.

    Depth of Plan is an Important Consideration of Natural Ventilation

    Natural ventilation, as the name suggests, is about supplying and extracting air to a building without the use of mechanical systems. Wilf says that one of the most important considerations in this process is the depth of plan, because with a very deep plan of building a lot of air has to be moved from one side of the building to the other. Springfield House is a ‘u’ shape so that the plan never reaches a depth of more than 4 metres.

    Springfield-House-model-(overhead)

    A model of Springfield House (overhead view)

    Other aspects that important are high ceilings in order to stop the heat building up at the top of the ceiling space and a high façade to pull a lot of air and wind around a certain area.

    The Stack Effect Helps Drive Air Through the House

    Due to differences in pressure – utilising the stack effect – air is driven through the house from a low point in the extremities, up through the core and out of an openable Velux window over the stairs.

    Springfield House is angled towards the prevailing wind to get maximum use of natural ventilation but because of the stack effect no matter which direction the wind is blowing, it’s still going to pull air through the building.

    Occasional Purging of Air is Necessary in Winter

    Although the building does not need to be ventilated constantly, it will need to be purged every so often. For example in winter, you’d want to keep the windows closed most of the time in order to retain the heat. Opening a window for 10 seconds will wash all the smelly air out and bring the fresh air in without losing much heat.

    Springfield House’s core also separates the two living spaces, which means the core can be purged independently.

    Air Quality Can Suffer if The Structure is Too Airtight

    In a naturally ventilated house there is no reason why it cannot be quite an airtight structure. However, if it’s too airtight one of the dangers would be that the quality of the air in smaller rooms on the extremities of the building might suffer.

    More High Quality Components Need to be Made Locally

    Springfield House takes a fabric first approach but Wilf is concerned that getting the right products comes at a large cost in embodied energy. For example, manufacturing of high-end Passivhaus standard products is done in Central and Western Europe, which must then be shipped in.

    Springfield-House-(visual-from-east)

    ‘Low Technology’ is About Letting the Design do All the Work

    Springfield House has two periscopic entities that look out over the site. This not only takes advantage of the views but it’s about the sun. The 1200mm overhang stops all the sun coming into the house in the summer whereas in the winter the angle drops to about 16º (in the UK) and most of the sun can then pierce through the building, heating it up. This low tech approach has been in existence for centuries.

    Springfield-House-(visual-from-north)

    Trees Provide Solar Shading

    Using trees is another way to improve the efficiency of the building. In summer when the trees are in bloom less sunlight can reach the house whereas when once the trees have lost their leaves more light can enter.

    Knowledge Needs to be Passed onto Successive Owners of the House

    Wilf’s client very much wanted a house that requires a hands-on approach. As this is slightly different to other houses it’s important that the user understands how it works. So, if this basic knowledge were not communicated to a new owner then there might be a problem.

    In the same respect, new occupants of a Passivhaus would need to understand the impact opening a window would have on the building dynamics.

    Mechanically Ventilated Air is Different to Fresh Air

    Wilf believes there is a big difference between fresh air and mechanically ventilated air. He uses the example of how he really likes the experience of feeling fresh air coming in through a window onto his face.

    It’s also about losing touch with the environment outside because the air has been filtered of smells and so forth.

    Upfront Planning has Been Key to Keeping the Costs Down

    A lot of work has been invested upfront to try and source local materials and reduce the environmental impact of Springfield House. Wilf talks about three western red cedar trees from the neighbouring woodland that have been earmarked for the cladding. By using a mobile sawmill this will keep the cost down as well as the need to transport materials.

    Wilf also gives another example of how the house will be built into the bank and the spoil will be used to re-landscape rather than sending it off to landfill.

    The Thermal Mass Provides a Natural Control System for the Heating

    Springfield house has an oversized concrete stair at the core of the building. While it is not ideal from an environmental standpoint, if specified carefully it can huge benefits as the thermal mass of the house. This will store the sun’s heat during the day, especially in the winter, and give back gently to the building. Also in the summer it will provide cooling because rather than that heat being in the air it’s in the concrete. As the core can be shut off from the main living spaces it can be quite a good way of providing a very natural control system for the heating.

    The Timber Frame Sequests Carbon

    Springfield House will have a timber frame that is a stick build. This means they are going to build it on site rather than importing a prefab frame from another country (for example). Part of the thought behind using a timber frame is that it sequests carbon. In other words, if the building lasts for 200 years the carbon would be locked up in the timber. Otherwise, in that same time, the tree would have started rotting and slowly bringing the balance of carbon in the atmosphere back down again, which is one of the problems we’ve got with global warming.

    Transcript

    Download a transcript of the interview with Wilf Meynell.

    Our Question for the Comments Section

    Is your build guided more by low energy design or environmental design?

    Cropthorne Autonomous House

    Read the blog post about Mike Coe and Lizzie Stoodley’s autonomous house. Find out where they got their inspiration, why it means they have a stronger connection with their environment and how it puts them in a good position for the future.

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