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.

Septic systems and toilets

“A properly functioning septic system, together with the maintenance of natural shoreline buffers and protection against soil eroding into the lake, is the most important measure cottagers can take in safeguarding their lake’s water quality,” says Gord Nielsen, an aquatic biologist in Bracebridge. “Phosphorus from improperly treated sewage has a direct effect on the amount of algae in our lakes.” A standard installation – consisting of a tank, an effluent distribution system, and a tile bed in which the effluent is dispersed – is the best first option for most family cottages. (Advanced systems, which might include an aerobic treatment tank or a bacterial culture, are designed to provide acceptable treatment in a smaller space.)

A promising new technique to remove phosphorus from effluent (still in the early stages of implementation) uses a specific type of soil – known as pre-Cambrian B Horizon soil – in and around the tile bed. The high aluminum and iron content of these soils – which occur naturally on many cottage sites or can be locally sourced – binds phosphorus chemically and physically. The septic contractor and the municipal health officer will help you determine the best location for the tile bed; in general, the farther from the lake, the better.

Reducing the effluent flow to the septic tile bed minimizes the risk of untreated or partially treated water escaping. Graham Smith, also a partner at Altius, suggests installing low-flow (six-litre) or, even better, dual-flush (three-litre/six-litre) toilets to reduce wastewater. Composting toilets, which use little or no water, work well where a traditional septic system can’t be installed, such as on small rocky islands. They are a sensible option when adding a second toilet, especially if the extra septic load of another conventional toilet is a concern. But choose a composting toilet that suits your usage patterns. To function properly, some models need to be used regularly, or the culture that does the composting dies. If use is infrequent, an outhouse is a tried-and-true option.

Renewable energy sources

Solar panels convert sunlight into electricity via photovoltaic cells. Today’s lightweight panels can easily be attached to just about any roof. Photovoltaic electricity generation doesn’t produce any emissions at point of use and the power source will not run out in the foreseeable future. But consider whether your energy needs and usage patterns make solar a wise choice:  In a seasonal cottage with high energy demands, it may not make financial sense as the upfront costs can take many years to recover. Paul Dowsett suggests a rule of thumb – if your cottage is more than 400 metres from a power line, your bank account may be better off with a solar or wind system than a hydro hookup.

There are also many solar water-heating systems on the market: flat plate collectors that can be winterized and systems in which a metallic solar collector is suspended inside clear vacuum tubes. All require a storage tank and, likely, an auxiliary water heater, which uses a small amount of energy to boost the temperature from sun-warmed to hot, if needed.

Other renewable options include wind power and geothermal (also known as water- or ground-source) heating and cooling. While these, like photovoltaic panels, are certainly eco-friendly, they may not be appropriate for your cottage. Wind turbines are only cost-effective in areas with good and reliable wind (breezes are not enough); a geothermal heating system works best in a well-insulated building with a constant, moderate demand for heat.

Backup systems and generators

Being green shouldn’t end when there’s a power failure. While the conventional back--up solution – a gas generator that powers an electrical subpanel – keeps the refrigerator and a few lights on, it also produces emissions and noise. Adding a muffler and specifying a propane or diesel generator (that runs on biodiesel) make the backup system more environment friendly, but there are even greener alternatives. A battery bank that’s charged by regular hydro could power a cottage for a week, depending on its size and the cottage’s energy needs. Where smart meters are available, the charging could be set for off-peak hours, when electricity is less costly. Battery backups can be designed to come on automatically if there’s a power outage and create no local emissions or noise. Another option is to use hydro for everyday cottage needs, but install a small solar or wind system just big enough to charge a battery backup. If you also install a net metering system, as long as the batteries are charged, the excess power from your solar or wind system goes back into the grid, saving you money on electricity bills.

In the end, says Graham Smith, dealing with power failures comes back to the cottage itself. A well-designed structure can eliminate many of the problems cottagers try to overcome with technology (think air conditioning or space heating), and minimize the electricity need in the first place. In the winter, for instance, a properly insulated cottage that’s sited to take advantage of passive solar heat and equipped with a carefully designed plumbing system should stay warm enough to keep the pipes from freezing, with little or no artificial heating. What’s more, installing energy-efficient appliances and maximizing natural light reduces the size, complexity, and cost of any backup system. What’s true for emergency power also goes for the actual cottage. “The bottom line,” says Smith, “is that conservation by design is still the first and best option to consider.”