Passive House (Passivhaus) is probably the worldwide leading standard for energy efficient buildings. It is a concept that has come out of Germany where the principal problem is keeping your home warm in the winter. Effectively no heating is required in a passive house even though it may be minus 10C outside.
In Spain there is a wider variety of climatic conditions to deal with than in Germany. While it is always mild on the coast there is still a heating problem in winter. Certainly there is a heating problem inland in Spain in the winter and there is also a significant cooling problem in the summer.
What can we apply from Passive House method in Spain? Well the key principals are:
1. Super insulation (that includes windows with a low e-value and carefully placed and orientated)
2. Airtightness
3. A mechanical ventilation system and heat exchanger
All of this will help keep your home warm in winter as well as cool in the summer. In the summer the mechanical ventilation and heat exchanger can work in reverse and expel hot dirty air from the inside and impel clean cool air from outside exchanging the heat as passes through the heat exchanger.
In order to achieve Passivhaus certification, a building must achieve airtightness of less than or equal to 0.6 air changes per hour, under test conditions. Airtightness is an essential part of creating an energy-efficient building and is a Building Regulations requirement. According to NHBC, home energy use is responsible for approximately 27% of the UK’s carbon dioxide emissions. A 2002 report from the BRE found that air leakage can be responsible for up to 40% of heat loss from buildings. Buildings designed to Passivhaus standard achieve a 75% reduction in space heating requirements compared to standard practice for new buildings in the UK.
What about outside living? Do we want an airtight villa in Spain to the same standard?
Firstly all well designed, well built, buildings should be airtight to a far greater degree than is usual in Spain.
Secondly, as northern Europeans, we are in Spain to enjoy the wonderful climate. In fact we want to spend most of our time outside. We need carefully blended inside / outside spaces that offer shade in the summer, sun in the winter and that are orientated for our pleasure, that is to say to enjoy the views, somewhere to dine and maybe cook outside at different times on the day and in different seasons. We may want a well ventilated building depending on how we are cooling the building and this is the opposite of air tightness!
In an ideal world we would have an inner space that is airtight into which we can retreat for those few months when it is too hot in the summer and too cold in the winter. For the rest of the year we need to be able to open up our home to the garden. We should be thinking of large shaded windows, perhaps even glass walls. The design of the terraces and outside spaces are just as important as the inside of the house.
Author: John Wolfendale
Bio: John is a founder of Eco Vida Homes and is passionate about bringing modern design and construction practices to Spain. He believes a home which is warm in winter and cool in summer is largely a matter of design and selective use of materials. He is British and a Chartered Surveyor with over 22 years experience living and working in Spain.
