MVHR and building physics knowledge for healthy, comfortable and energy efficient homes
Why aren’t passive houses (AKA Passivhaus) mainstream? Why isn’t every new home built in the UK produced to the design specifications of passive houses? Here I’ll go through what’s bad about passive houses, whether it’s true, and what might be done to fix the problems. 1) Passive Houses are boxy and ugly Passive houses are … Read more
The Passive House Form Factor quantifies the relationship between the living area of the building and the total amount of surface area that heat can escape from. The calculation is simple: Total heat loss area ÷ floor area = Form Factor The Form Factor of a building is key in low energy design because it … Read more
When we talk about “low energy homes”, what are we really talking about? Well, when we’re trying to build low energy homes what we’re figuring out how to use the lowest amount of energy to heat the entire space in your home to a comfortable 20DegC (and how to keep it at 20DegC). Where does energy come from … Read more
Today Professor David Mackay of the Department of Physics in Cambridge and former Chief Scientific Advisor to the UK Department of Energy and Climate Change (DECC) lost his battle with cancer. Professor Mackay was the reason a lot of my colleagues moved into low energy design, microgeneration technology and sustainability industries. He was one of the … Read more
Are eco-friendly passive houses for rich people? Eco warriors? Self-builders? Housing associations? Or are they only the preserve of our more logical, engineering-minded continental cousins in Germany? Passive Houses are for everyone. To build a Passive House, ie, one that runs at ten per cent of normal household bills, doesn’t need any extra technology like air-source heat … Read more
One of my friends remarked today that their colleague was asking about that “German eco home, the one where you can’t open the windows…” The idea that you can’t open the windows in a Passive House comes from a misconception regarding the clever way that Passive Houses regulate the heating and cooling of a home. … Read more
The number assigned to a building fabric element (eg, a window) that represents its thermal resistance is called its U-value. A U-value tells us how quickly or slowly it takes for heat to pass through it. Fabrics with lower U-values are better insulators than those with higher U-values. Part L of the UK Building Regulations … Read more
Modern homes are shifting towards increasing levels of airtightness in order to secure heat-saving benefits. With increasing levels of airtightness comes a need for a ventilation strategy. For Passivhaus, this means an MVHR system. Heat from the home is lost in two ways: through the fabric elements as it passes through our walls, windows, doors, … Read more
Not many UK builders have embraced PassivHaus principles yet. Below are a few ways that builders in the UK can ruin low energy homes, either by ignoring or failing to understand the new wave of low energy design and build techniques that help create modern, ultra-comfortable, money-saving eco homes. 1) Ignoring the airtightness membrane UK Building … Read more
We spend a huge part of our lives indoors – I’ve spent 96 per cent of my last 24 hours indoors, and it’s not an unusual day for me in winter. Consider your day. How long were you actually outside in the sunshine (or rain) altogether today? During mid-winter in England here was my typical day: … Read more