Geothermics at the Centre for Sustainable Development
With 32 earth tubes installed directly beneath the surface of the building, the Centre for Sustainable Development stands out for its innovative use of geothermics in a commercial building in Montréal.
The installed technology will make it possible to heat and cool the building via the exchange of heat energy with the ground. In addition to generating substantial cost savings, the Centre will also significantly reduce greenhouse gas emissions.
Geothermal technology uses underground pipes (inserted vertically below the Centre) carrying a fluid (water mixed with ethylene glycol, an antifreeze agent) that adopts the ground temperature (12.08ºC on this particular site) before being returned to the building’s heat pump. At 12°C, the temperature of the fluid circulating in this system is markedly higher than low winter air temperatures (as low as -25) and far below summer peaks (+32).
These differences in temperature account for the energy potential of the system, in that a heat pump has the capacity to “concentrate” the heat and cold to the extent that it becomes possible to heat and cool the Centre. So in winter, the Centre transfers thermal energy from the ground to the building for heating purposes, and in summer, the direction of this heat exchange is reversed to cool the building down.
Key facts and figures:
- Estimated annual savings: 300,000 kWh, or the equivalent total amount of power used by 15 average single-family homes;
- The geothermal energy comes from the sun, which heats the ground, as well as from the heat present in the earth itself. It is a clean source of free energy that remains stable over time;
- Using geothermics prevents greenhouse gas emissions (just the opposite of other systems);
- For each kilowatt of electricity used to operate a geothermal system, over 3 kW of heat energy is removed from the ground.
For more info…
- Earth-Energy Systems – Canadian Office of Energy Efficiency
- Natural Resources Canada
- 5/5 Monde show on TV5 (in French) - “Questions sur la géothermie,” January 15, 2006
Centre for Sustainable Development building envelope
The envelope of a building serves to diminish energy transfers between the interior and the exterior and to protect certain components of the structure from the effects of humidity and sunlight.
Air-tightness from exterior to interior
The exterior cladding and the weatherization membrane prevent wind-blown rainwater and moisture from penetrating the walls and damaging water-sensitive materials.
Air-tightness from interior to exterior
The thermal resistance of a wall or roof, or its capacity to let heat and cold pass through it, depends on at least two factors: the average thickness of the insulation along the entire exposed surface (including any areas where insulation is not possible for technical reasons) and the thermal resistance of the materials used (R-value or RSI). The Centre for Sustainable Development will exceed Canadian thermal resistance requirements for walls by 16% and for roofs by 62%.
Thermal bridges
The building’s air-tightness and thermal insulation can be compromised by structural components such as columns, studs, pipes, beams or concrete slabs. These weak spots in the insulation, known as thermal bridges, can account for 30% of an insulated building’s heat loss. Several techniques can be used to eliminate thermal bridges or to minimize their impact.
In planning the CSD project, the designers have paid special attention to minimizing the impacts of thermal bridges. In addition, a specialized firm was hired to review all details of the building envelope and to recommend any necessary improvements.
The most recent energy simulation performed indicates that the CSD will exceed Canadian energy consumption requirements for buildings (MNECB) by 60%.
Windows
Generous fenestration is something that users generally like to see in nearly all types of buildings. However, because of their lower thermal resistance value (±10% that of an insulated wall), windows can also be a major source of heat loss, thus compromising a building’s energy efficiency. Aware of this paradox, the CSD will opt for high-performance fenestration systems, generally comprised of triple-pane windows filled with argon gas and having a double low-emissivity coating.
For more information...
- Building envelope and energy efficiency – Office of Energy Efficiency of Canada – Natural Resources Canada
- Conseil de l'enveloppe du bâtiment du Québec [Quebec Building Envelope Council]
Lighting strategies at the
Centre for Sustainable Development
Lighting generally accounts for between 20 and 25% of the energy consumed by an office building. It is thus ecologically essential, not to mention economically profitable, to invest seriously in reducing the amount of energy required to light such buildings.
It is with this in mind that the designers of the Centre for Sustainable Development have strived to optimize the use of natural light to illuminate the building’s interior spaces. Concretely, this has translated into the presence of a large glass wall as well as the careful coordination of the positioning of the windows with the layout of interior spaces. This approach will make it possible to substantially reduce the blocking of natural light by internal partitions, columns or furniture. In addition, in order to meet strict requirements regarding access to light and a view, most of the partitions forming the walls of offices and meeting rooms will themselves be made out of glass.
The use of high-performance lighting devices that emit only a small proportion of the energy consumed in the form of heat will make it possible to produce more light using less energy. T5 direct/indirect lighting fluorescent tubes will be used to illuminate work spaces, while light-emitting diodes (LEDs), which last 100 times longer than traditional incandescent lights, will be installed in traffic areas requiring lower light intensity. The number of lights installed will provide all workers with 300 lux, which is the recommended light level for most office tasks. Only a small number of offices will be equipped with supplementary lighting, necessary for certain less frequent tasks.
Finally, electronic tools will be used to ensure the most efficient use of lighting devices. The main goal of these tools will be to lower artificial light intensity in the presence of natural light (light intensity detectors) or simply to turn lights off when no one needs them (motion detectors).
