The conserving cottage

How to build or retrofit a greener getaway

by Susan Nerberg

Illustrations by Greg Latimer and Amanda Reed, Levitt Goodman Architects

Click on detailed illustrations to enlarge.

We’ve all heard the news about climate change, and people are reacting by doing their bit for the planet. Making your cottage more sustainable is no exception. But for many, the word “green” conjures up images of a utilitarian, less-than-cozy retreat with unsightly solar panels strapped to the roof. Not so. And while the off-grid cottage powered by only sun or wind is still a rarity, many energy- and water-saving principles can be worked into any structure. So whether you’re renovating or building new, here’s what you can do to go green.

Site selection and preparation

“The greenest thing you can do for nature is to leave it alone,” says Trevor McIvor, an architect with a keen interest in sustainable design. “When this is not an option – as in building a cottage – minimize the disruption.” The starting point, he says, should always be with site analysis and building placement on the lot. The orientation (north, east, south, or west), topography, vegetation, and unique natural features, such as exposed granite, all inform the cottage’s design, while shoreline and side lot setbacks specified in by-laws limit its location within the site. “We tend to play off natural features, stepping the building down existing slopes,” says McIvor, who’s spent almost a decade designing cottages and overseeing their construction as a partner with Toronto-based Altius Architecture.

Making the cottage fit the topography – not the other way around – saves the -parcel from blasting and extensive grading and landscaping. It also spares existing trees and other vegetation, which provide habitat for birds, butterflies, and other wildlife. As well, a conservative approach to site work preserves as much as possible of the ground cover and root mass, minimizing soil erosion, especially during the spring runoff.

Keeping cool – or staying warm

When siting the cottage, consider passive strategies for summer cooling and winter heating to reduce energy use. “There should be no need to artificially cool a well-designed cottage,” says McIvor. Take advantage of prevailing evening winds for cooling in summer. A wind trap, or raised vent, on the roof pulls hot air up and out, drawing cooler air in below, while strategically placed windows can be opened to increase cross-ventilation. Ideally, each room should have opening windows on at least two walls. If this isn’t possible, install an opening transom window over the door (lets warm air escape) and a lower opening on the exterior wall (draws in cool air).

To bring in natural light and for solar heating in winter, orient the cottage to the sun’s path, with lots of glass on the south side for solar penetration. Thermal-mass flooring, such as concrete, brick, or stone, can passively warm the cottage from October to May by absorbing heat from low-angle sun and releasing it at night. (Thermal mass refers to a material’s ability to absorb heat energy.) But beware in summer – without proper shading, all that radiant heat can turn the cottage into a sauna. To prevent this, keep the sun out from June to September by building properly sized eaves (on existing cottages, eaves can be extended when re-roofing), awnings, horizontal trellises, or exterior louvres. Once this is done, the thermal mass helps cool the cottage in summer. “If you keep the floor shaded during the day, its temperature will be lower than that of the air,” says Peter Busby, one of Canada’s foremost experts on green design and a principal with Vancouver-based Busby Perkins+Will Architects. “Expose it to night air, and it will keep the space cool all day.”

The windows themselves can either block or admit the sun’s radiant energy. Most new windows have a low-E (low--emissivity) coating to reduce radiant heat flow. Because such windows let radiant energy in but not out, they work best with exterior shades. On older windows without low-E coating, light-coloured blinds or curtains reflect radiant energy out.

Another way to retrofit an existing cottage for solar gain is to add opening skylights, with shades that block the heat while allowing light in. They open to create nighttime convective ventilation even when there’s no wind. Ceiling fans – or a dip in the lake – do the trick on very humid days or when airflow is stagnant.

Proper insulation minimizes heat gain in summer and heat loss in winter; it’s one of the best ways to curb energy use year-round. Sprayed-in-place foam and foam panels tend to provide more R-value (resistance to heat transfer) per inch than batt or other rigid board insulation. “But insulation performance should be looked at in a larger context,” says Paul Dowsett with Scott Morris Architects in Toronto. “Consider how much energy it takes to make the material. Is it using non-renewable resources? Can it be recycled at the end of its lifespan?” Commercially available green insulation can be made from recycled glass, mineral wool, cotton, or soybeans. Whatever your choice, consider the product’s potential for releasing harmful gases or supporting mould growth, and keep in mind that since there are creatures that love to use some insulation as take-out bedding or live-in housing, not all types may be suitable. Alternatives to traditional stick-frame construction include structural insulated panels (SIPs) and insulated concrete forms (ICFs), which provide all-in-one options suitable for new cottages. Straw-bale construction provides R-values comparable to those of super-efficient homes. “Straw bales also take less energy to produce than most conventional insulation,” says Dowsett. “It’s a natural material that can easily be returned to the earth at the end of its life cycle, especially if sealed with a clay-based plaster.” A green roof – a roof structure with living plants in a layer of lightweight growing medium – is another effective way to insulate. If you are retrofitting, start insulating at the top – roofs and attics are major contributors to a cottage’s heat loss or gain.

Next:

Part 2 - Septic systems and toilets, renewable energy sources, back up systems and generators

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