Discovering Colorado, the cradle of passive houses

A few weeks ago, for professional reasons we visited Denver, Boulder, Aspen and surrounding areas, in Colorado.

At the foot of the Rocky Mountains, in the hearth of the United States, this region saw some of the very first passive buildings being built in the world, thank to the Rocky Mountain Institute, founded in 1982 by Amory Lovins in Snowmass. We had a chance to visit this extrahordinaire building, which we described in its own article.

View of the Rocky Mountain Institute
South façade of the Rocky Mountain Institute

Thanks to the kindness of so many local colleagues and contractors we met, we also had the chance to visit several construction sites of low-energy buildings and passive houses. The overall experience was very interesting, allowing us to compare our European experience with a reality that is very different from it in terms of mobility, use and life span of buildings, use of energy and resources, and so on. In the eyes of a European, the USA remain a land of contrasts, with interesting lessons to be learnt.

One of the first “passive” construction sites we visited was located in Berthoud, thanks to Harrington Construction.

The interior of the Berthoud passive house
The interior of the passive house, before the packing of the cellulose insulation in the perimeter walls.

Construction techniques used in the US are evidently different from the ones we’ve used to far, for example in the two passive houses we are currently building in Cavriago. Nontheless, the construction quality remains high, to guarantee the level of comfort and energy efficiency of a passive house thermal envelope.

A second example of a passive building, in Boulder, was shown us by Mark Attard of AE Building Systems, a company specializing in products and components for low-energy buildings.

A passive house in Boulder
View from the inside of the passive house of Boulder, looking down onto the valley.

We also had the chance to visit some buildings with energy retrofit, as in the case of a house in Louisville, where the existing structure was insulated with rockwool (for the perimeter walls) and expanded perlite (for the slab on ground). Overall speaking, the peculiar climate of Colorado, which is very dry year round, allows to easily solve some retrofit problems that are particularly risky in our Italian climate, which is on the contrary very humid.

The thermally refurbished crawl space
The crawl space, with perlite insulation under the black sheet.

At the Alliance for Sustainable Colorado (which brings together several associations around the topic of environmental sustainability), we assisted to the presentation by Ashley Perl of the City of Aspen, about the effects of climate change on the city and its economy. The overall raise in temperatures is leading to a steady decrease in snow fall, and to the shortening of the skiing season. For climatic reasons, therefore, the city of Aspen is forced to re-think its entire economy.

The city of Aspen, with its 6.000 permanent residents, currently employs four people in several activities to diminish the environmental impact of the city. The “Canary Initiative” specifically includes a variety of initiatives to reduce consumption of energy and water, as well as to promote waste recycling. Given the small size of the city, its initiatives are generally used as pilot projects for the entire state of Colorado.

Among other meetings, we also had the chance to visit Alpen Widnows, the company producing some of the most performing windows currently available on the American market.

Alpen Windows
A window by Alpen Windows. The balloons are used to compensate the pressure difference between the glazing and the surrounding environment, caused by the high altitude.

Last but not least, we assisted to the presentation by Andrew Michler about his book “Hyperlocalization of Architecture”, which summarizes the state of the art of architecture in several countries around the world. The book also includes interviews with several eminent people such as Wolfgang Feist, founder of the Passivhaus Institut.

Andrew Michler
Andrew Michler during the presentation of his book.

Overall, our trip to Colorado was very enjoyable, besides our professional meetings. We also managed to meet with old friends, have breakfast with donuts and dinners with elk burgers and craft beer. You can’t live on passive house alone.

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