THE DRAWING BOARD-September 2010

This month’s Drawing Board is the third in a series
of four installments by architect Jeremiah Eck about the progression of a house in Lovell

I’m old enough to remember the original solar movement of the 1980s, an admirable goal at the time but one that quickly turned into a short-lived technical flash. Many claims were made about sustainability for the future, but few, if any, of the declarations came true. I’d be hard-pressed to point to any lasting residential example representing that so-called Age of Aquarius.

It is certainly true that some improvements were made at the time, such as more efficient and smaller heating systems and higher R-values for windows. Recently, photovoltaic solar, solar heating, geothermal, and wind systems, supported by tax incentives, are providing updated ways to generate energy and reduce our dependence on fossil fuels. But like those of the eighties, I believe that these new technical advances alone will not make our homes lastingly sustainable. What we need is a more sensible approach, and this house in Lovell is a good example.

In the first article on sustainable siting, I pointed out the compromise we crafted between the glass-filled view to the west and the long, south-facing roof of photovoltaic panels. The photovoltaic system along with a geothermal well will provide a good deal of electricity and heat for the house, but for the sake of discussion, let’s imagine that we didn’t provide those energy producers and relied instead on less technical energy savers. It was always our primary intention to design a house that could be called sustainable even without that added advantage. In the pursuit of such a sensible sustainability, I believe firmly in two key principles. The first is that it’s a lot cheaper to save a BTU than it is to produce one. The second is that materials with long-lasting and low-maintenance qualities are also great energy savers. Here, we applied both principles.

Although it’s obvious that the glass in exterior windows and doors is where the biggest energy loss occurs, it is the wall and roof section that is the cheapest place to save energy, and in this house, we did all we could to provide substantial insulation for those elements of the house. The sketch above shows a typical section through the house. It’s a technical drawing that would probably cause most homeowners to yawn, but the big change from typical insulation is the use of taped rigid insulation over the exterior plywood sheathing and spray foam insulation in the wall and roof cavities between framing members. The net effect is a cost-effective, continuous-sealed house envelope that is far better than typical batt insulation and vapor barrier construction that, in spite of the best intentions, is always pervaded with air penetrations and therefore energy loss.

The other area of sensible sustainability is in the choice of materials, especially on the exterior. Nothing is more sustainable than a material that is long lasting and relatively maintenance free. Here the use of clad windows, PVC trim, and stained natural cedar along with the most durable material of all, stone, will give the homeowners a lifetime of low maintenance. They may be more expensive in the short run but not over the long term. Even without its advanced technology, in this era of increasing energy costs, this house demonstrates the future of a better and more sensible sustainability.

Eck | MacNeely Architects: eckmacneely.com, 617-367-9696