For Brian McGarry, an economics lecturer who built a family house based on passive housing criteria in the Pyrenees this year, the arguments look compelling. As his first full winter in the lowenergy house draws in, we asked him to keep us posted. Do passive houses work?
I had never heard of a passive house in February 2012, when I purchased a plot of land in a Pyrenees village at 1,200 m altitude on the Spanish-French border, embarking somewhat reluctantly on a self-build housing project. I knew what I wanted: a comfortable, aesthetically pleasing and economically sensible house in an attractive location. And I knew what I didn’t want: a costly project management nightmare for a novice builder.
What I didn’t know is that I would be persuaded to build a pre-constructed, custom-designed house based on energy-efficient passive house criteria. Some European economies are already demanding levels of energy efficiency that are close to those standards, but the simplicity and logic of the proposal proved overwhelming: it promised to be easier and quicker to build, cheaper to run, and more comfortable to live in. The objective was not to meet standards such as those of Germany's Passivhaus Institut, but to incorporate the fundamental concepts of passive energy management into my project: an airtight and highly insulated building envelope; large southfacing double or triple-glazed windows (if possible, filled with argon gas) that passively capture the energy of the sun; a heat recovery ventilation system to provide fresh air; and a simple, low-cost heating system consisting of a modern wood-burning stove, a bathroom heater and a portable radiator backup for when the sun doesn’t shine and temperatures plummet. No significant limitations were placed on the design, the risk of a budget overrun for a highly specified factory-built structure looked low, and it had excellent environmental credentials. Moreover, the cost was no more than a conventional build.
Certainly, arguments against the project could be made, such as the uncertain resale value of innovative houses in a conservative market, and the risk of being an early adopter of technologies that are relatively new to Spain and France.
A German architect recommended a young Catalan colleague, Josep Bunyesc, to do the job for me. In 2009 Bunyesc. designed the first house in Spain based on passive house criteria, built in conjunction with an innovative industrial specialist in wooden structures, Fustes Sebastia. I was deeply impressed by the houses I visited–the functionality, comfort and spaciousness of the designs, coupled with the efficiency, quality and cost of the construction method. I then hammered out a design with the architect–the longest part of the process.
The rest was disconcertingly fast: a USB pen drive transmitted the design orders to an automated woodcutting and assembling factory in Spain. A total of 22 insulated wall and roof structures were completed in three weeks and, with most windows also fitted, these were transported by truck to the plot location across the French border. The house was then assembled on site by local housebuilding specialists, Ecobois.eu, who took another week to close the structure, despite adverse weather conditions in February 2013.
What are the main performance results so far?
After six months in use, the house is proving to be both cheap to run and remarkably comfortable–staying cool in the hot summer was effortless, as long as the windows were shuttered or shaded from the sun. Now staying warm in the cold, high-altitude December climate also seems easy, so far. The temperature remains even throughout the building–no hot or cold rooms–and the dynamics of the building’s passive heat management mean that once the sun shines with reasonable regularity, the house stays comfortable, even when empty. Arriving on a cold night after an extended absence has so far not been a concern.
Winter arrived in force in the Pyrenees in November, with abundant snowfalls and temperatures as low as minus 8° Celsius. Though early days, the house has responded well: the stove is lit during cold evenings but the portable radiator has not yet been needed. This type of construction seems not only to make economic and environmental sense, but to enhance our quality of life, too.
Brian McGarry will post a monthly update of his first Pyrenees winter in his passive house at www.oecdobserver.org.
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© OECD Observer No 297, Q4 2013