Building high performance homes in cold climates, pose a unique challenge to architects. Temperatures in cold regions can be in the range of 20 °C to 30 °C in summers and -25 °C to -30 ° C in winters. Problem solving is required in areas of energy efficient heating, water shortage, waste management and availability of construction resources. Cold regions are located at higher altitudes so transporting material is a challenge. Hence locally available material like wood and stone, are preferred.
Successful architects have been creating high performance homes using some very easy tricks. These include design hacks, creating energy efficient systems and reducing long-term operational cost for residents. It is essential to address challenges such as prolonged winters, extremely low temperatures, torrential downpours, snow accumulation and high velocity winds. The goal is to prevent heat loss and promote heat gain. Here are some ways that an architect can build high performance homes in cold climates.
In cold regions, most sites would be on a slope. It is best to choose the side of the mountain/hill, with maximum heat gain and access to solar radiation. This helps reduce usage of heating systems. Winds too increase the draft and reduce temperature in homes. Instead of windward side, always choose the leeward one.
In case the site happens to be in the direction of the wind, use glazing as a protective measure. Architects can also smartly use naturally available reliefs as natural wind barriers. In case of multi-home projects, designers can place homes close together, to reduce wind exposure. Architects can place living areas in the direction of the sun and storage/utility areas in the colder parts of the house.
Architects should keep in mind certain easy pointers when designing the basic structure of the house. Stairs, parking areas, balconies and entrances shouldn’t be located under the eaves. Ensure the design prevents formation of ice dams. Gutters should not be used in locations with high expected snow load. Facing the house towards the south, reduces the need to use external snow melting devices.
Sidewalks, walkways and entrances can be protected using overhangs. Avoid placement of ducts and furnaces in the attics as this can lead to formation of ice dams. Basements should be well insulated. It is recommended that one uses highly durable yet low maintenance products for exterior. These include composite decking material, stained cedar wood, stone and fibre board.
To create high performance homes in cold climates, it is essential to optimise the roof design. Insulation is key as it helps retain heat inside. Most designers create false ceilings filled with insulation material such as wood wool, polyurethane foam and thermocol. Further they add a layer of aluminium foil between the roof and insulation to improve insulation.
There are more advanced insulation materials available nowadays but they tend to be expensive. A very basic step to make the roof as inclined as possible as this would allow snow and rain water to drain down efficiently. Skylights on southern facing roofs along with solar heat collectors are a good way to harvest naturally available heat.
Snow needs to be accounted for, when planning high performance homes in cold climates. Roofs are key focus area with this regard. You need to build steep roof slopes and any elevations on the slope should be avoided. Chimneys and vents need to be positioned right at the top. If designing skylights, ensure that they are elevated and are made of a slippery material. Traditionally used material such as wood shingles and slates, tend to make snow stick around longer. As mentioned earlier, avoid gutters. The edge of the roof could have an ice shield membrane.
Snow also tends to collect on the ground and on cars, making movement difficult. This leads to the need for regular shovelling. If the site area is large enough, accommodate car parks or an interior garage. Cover the drive-way and provide railings at the side, so that people walking, can hold onto it for comfort. There are energy efficient snow melting or de-icing systems available, which can also be invested into.
Architects should be aware of the R-value (a material’s resistance to heat flow) and the U-value (rate of heat transfer), when choosing material for building walls. The ideal values differ when one uses wood frames or metal frames. There are two aspects to high performance walls in cold climates- 1) wall components 2) control layers. The former consists of the cladding, exterior insulation, furring, cavity insulation and finally the interior finish. The latter consists of ventilation cavity/drainage space, water barrier, air barrier and vapour retarder.
Walls should be constructed such that there is optimum air barrier and enough retardation of vapour. For interior air barriers, architects use airtight drywalls, sealed polyethylene and sealing sheathing. For external air barriers, they use taped insulation, synthetic house wrap sheeting etc.
While we have spoken briefly about solar gains when discussing orientation, here are a few more points. Face the long side of the house towards the south. The shorter sides could face the west and east. Locate your windows to the south side to enhance their performance. It should be such that the window glass area falls over about 10% of the floor area. This what we call a sun tempered house. But ideally we should aim for a 20% coverage.
While new architects might find it counter-intuitive in sun starved regions, mounting solar photovoltaics on the roof has its benefits. It contributes greatly to building high-performance homes in cold climates. Watch out for the orientation and the tilt angle. Use overhangs to manage heat gains. Nowadays, one can use easily available software to determine the right degree and size of the overhang.
Fenestration is a key element of a high-performance home in cold climates. Dedicate most of the window area to the south for heat gain. Seal them effective and double glaze the windows. Try to prevent condensation that can occur in the air space between windows.
Use advanced designing techniques to incorporate air and water control systems, on windows. Once again, the U-value and R-value of materials matter. Preventing air leakage through window frames is also so pay attention to sealing.
Heating is essential for homes in cold climates. In recent times, many architects are trying to move away from the use of fossil fuels and non-renewable energy sources, for heating. Another important choice to make is if the heating system should be portable or central. The former tends to consume much more electricity, but offers the comfort of adjusting the heat in every room. However, in a central heating system, a central thermostat offers the efficiency of maintaining optimum heat. Such ideas are key to building high performance homes in cold climates.
In central heating one can choose among radiant heating, heat pumps and forced-air furnaces. Some homes use boilers too. Effectively the choice boils down to source of energy available- natural gas, fuel or ready electricity.
Building regular homes in cold climates is quite a challenge, let alone high performance ones. However, after managing a few projects, architects tend to grasp the key pivotal decisions that one needs to take. High-performance homes in cold climates are supposed to deliver, not just when they are new but for the decades to come. And the above pointers are sure to steer an architect in the right direction.