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Passivhaus is a standard that focuses almost entirely on the energy used by buildings. It has been very successful in demonstrating that livable and comfortable houses can be built using this standard in a variety of European countries and further afield.
It has had a major influence on the direction of policy in many countries, with some even adopting the Passivhaus standard as optional or mandatory in new construction. All of this is positive as it helps to drive the development of new products and skills in the construction industry, to create even more highly energy-efficient buildings.
The Passivhaus standard does have an impact on design to some degree — in the same way that almost all energy-efficiency standards have an effect. Simple volumes and shapes tend to work better than complex ones and the design of the building fabric needs to be carefully considered from the outset to ensure that it performs efficiently. The size and orientation of windows are also important to manage solar gains as well as heat losses.
However, none of this means that designing to the standard is difficult, and our project with Potton demonstrates that an architecturally interesting and relatively complex design can meet the standard. The challenge is to merge both the design considerations and energy-efficiency from the outset as highly energy-efficient buildings need to be designed to perform well from the beginning.
A design is not likely to be cost-effective or successful if it needs to be manipulated after creation to be more efficient. At HTA we include designers and energy-efficiency specialists on our staff, so we can ensure that the design is heading in the right direction from the beginning.
We use computer simulation tools to assess the designs at regular intervals to ensure that we are meeting the required standard. It is also vital that the voices of the designer, client and sustainability expert all have equal weight from the beginning of the process so they can trade-off judgements and opinions.
For this project with Potton, we tested three designs, choosing the one we knew would be the most complex to build from an energy-efficiency perspective. This was because it had the most potential to deliver an exciting design — and we didn’t think that the difficulties of achieving the Passivhaus standard were insurmountable.
The design centres around a small internal courtyard which acts as the focal point of the dwelling. This courtyard is surrounded by the staircase, the living room and the kitchen, and has a roof light that brings daylight into the heart of the home. The house features more accommodation on the ground floor than on the first floor — meaning in other buildings, the design can be varied to accommodate a larger number of bedrooms upstairs. We liked the idea that there could be many different versions of the home that would suit different lifestyles.
Yes, you can. While we have not added renewables to the showhome, there is plenty of roof space to accommodate solar thermal or photovoltaic (PV) systems. If you have a family with young children or teenagers, then solar thermal may offer the greatest savings as it can provide over half your annual hot water requirement.
Adding PV panels also helps to reduce National Grid energy consumption. Grid energy is not “clean” energy, as we still use a lot of coal and gas in the UK. PV panels can help reduce the energy used in a Passivhaus to nearly zero over a year — or even to generate a small income (via the Feed-in Tariffs) if there are sufficient PV cells and the energy use is well-managed by the occupier.
Read Part 3: The Details Behind Passive House (Passivhaus) Construction
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