The energy consumption of a passivhaus is significantly lower than that of houses built to conventional building regulations standards. This means they are significantly cheaper to run. The economic argument to build to passivhaus, is one of the strongest reasons to pursue this build standard.
Passivhaus energy consumption
An average UK house might use 140kWh/sqm/year for space heating, whereas a passivhaus is designed to use less than 15kWh/sqm/year. That is an incredible difference! The basic design principles behind this can be seen is our previous blog. You can also reference sources such as The Passivhaus Trust and Association for Environment Conscious Building.
Thermal comfort
So how does it feel to live in one of these houses and are these targets realistic? Well, the answer is that the targets are achievable and the experience of being in a passivhaus is such, that, you know you are in a very special house. This is more than just reviewing your energy bill, but something called ‘thermal comfort’, a direct result of the thermal efficiency of the building fabric, the airtightness and the MVHR (mechanical ventilation and heat recovery). The temperature is stable and consistent and there are no ‘cold corners’.
Also, crucially, it does not need to be expensive to build. With a good understanding of the building standards and supply chain of suppliers and builders, the costs can be comparable to conventional standards in our experience. However, it is important to bring in a team of architects and builders who have both the design experience and technical knowledge of the requirements on site.
Low energy buildings
Also, the aim of a low energy building, means that you don’t need as much heating equipment.
When we built our own house and home office in Totnes, Devon, to the standard, we had the opportunity of trying this out for ourselves. So we took a minimal approach to services and we built a house with no heating, (but put in the infrastructure to install it later if required). We lived in it for a year like this.
Simply occupying the building contributes to the temperature, which was helped further with passive solar gain in the winter months. The minimum winter temperature was 17 deg c, when the outside temperature was below zero for a number of days, and the maximum summer temperature was 24 deg c, during days when the outside temperature was about 30 deg c. The design temperature was 20 deg c, which it would stay at for most of the year.
This last winter, we put Adax heaters in at a total cost of £1,500. These are clever, cost effective, heaters, which can work off inbuilt thermostats to use very little energy to maintain a room temperature of 20 deg c. They can be operated from an ‘app’ on your smart phone and monitor the energy used by each room and collectively across the whole house. The results are true to the PHPP modeling used to design the house, with heating demand below the 15kWh/sqm/year. The aim is for this to be met entirely with solar renewable energy.
AK Architects
AK Architects are building on these experiences to provide a constantly improved approach to good value, affordable passivhaus and low energy building standards for private clients, communities and house builders.
We truly believe this could be, and should be, a mainstream approach to building new homes on the path to address the Climate Emergency. We put our money where our mouth is in this regard, and can help you invest wisely for the future.
Need further advice?
If you’d like to talk to us about a passivhaus project please do get in touch or take a look at one of our passive house projects.