Diagram: Exploded View of Building Components
The following "technologies" have been integrated into the retail building to achieve carbon neutrality:
- A daylight factor of 3% was achieved for the entire floor area, allowing it to be fully daylit and eliminate the need for electric lights during daylit hours. Daylight factors of less than 3% do not provide measurable daylight, only brightness. Daylight factors over 5% result in glare and too much glazing, reducing the overall insulating value of the building envelope that results in too much heat loss. This required a large north facing clerestory running the length of the building east-west, glazing on the house with integrated photovoltaic cells to both generate energy and avoid overheating and strip glazing along the north facade.
- Non-regularly occupied spaces such as washrooms and storage rooms are located in the core of the building and are fitted with occupancy sensors.
- Operable windows on the south facade, north facade and clerestory permit natural ventilation during shoulder seasons and summer when the outdoor temperature is within the interior comfort parameters, between 18C and 24C. Natural ventilation also operates at night if excess heat is accumulated during the day. This eliminates the need for the ventilation system to operate.
- The Window to Wall ratio is 32% and balances the area of glazing required for daylighting and view with the insulating value of the building envelope.
- The roof is air-tight and super insulated to R63 using 9.5" thick Structural Insulated Panels (SIPs) to avoid thermal bridging of structure and to facilitate disassembly.
- The walls are air-tight and super insulated to R43.2 using 6" thick Structural Insulated Panels (SIPs) to avoid thermal bridging of structure and to facilitate disassembly.
- Glazing is high-performance triple glazing with thermally broken aluminum frames, non-conductive edge-spaces, low e-coatings and inert gas fill.
- The concrete slab-on-grade acts as a thermal mass. It absorbs any spikes in heat gain to reduce cooling loads. Any heat absorbed is re-released when the temperature drops inside to also offset heating loads.
- The mechanical system uses in-floor hydronic heating to provide the most efficient kind of heating. Fed by a ground-source heat pump, combustion sources of heating are avoided and heat and cold are provided from the earth. This required the heating and cooling loads to be relatively balanced, another factor that drove the design of the project. Retail buildings, unlike office buildings and residential projects are not subject to the same pressures of individual comfort. Most staff are continuously occupied and shoppers are dressed for the outdoor conditions. Thus, a heating and cooling system that must quickly respond to small changes throughout the day is not needed, making an in-floor radiant system appropriate as its long lag times to change temperature is not an issue.
- The mechanical systems are all electrically based to allow them to plug into a renewable energy array and not involve combustion sources of energy that would lead to carbon emissions.
- Over a year, energy simulation suggests that annually the building will need 51,438 kWhr (86 kWhr/m2/yr or 8 kWhr/ft2/yr). This is met completely by a 37.8 kW roof-top photovoltaic array.
- The landscape incorporates a large bioswale with a diversity of plantings including trees, shrubs and natural vegetation and a grass-paver parking lot. These landscape devices not only manage on-site water, but also increase on-site biomass to increase the ability for the site to sequester carbon.