Net Zero Energy Buildings
Innovation in Sustainable Building Materials and Systems
Net Zero is the ne plus ultra of sustainable design. It refers to buildings that generate enough renewable energy, either independently or through a district system to meet all their energy needs annually. Not many buildings actually achieve net zero objectives, but many new buildings are being designed and constructed as ultra-efficient buildings with smaller carbon footprints.
Architectural Record’s (AR) Innovation Conference will highlight new practices and advances in technology for achieving sustainability. Deployment of advanced mechanical systems, together with judicious site orientation and material selection, can result in significant energy reduction.
The jury is out, however, on how successful many of these buildings will be in the long term. It is possible to generate onsite all of the energy a building would need, without actually diminishing the amount of energy a building uses and while still contributing to CO2 emissions.
Net zero/sustainable design implies more than energy self-sufficiency. Some Canadian examples illustrate best practices in sustainability with a minimal impact on the environment.
Trends in Energy Efficiency
One of the buildings to be featured at the AR conference on innovation is the Richard J. Klarchek Information Commons for Loyola University in Chicago. The design is by Solomon Cordwell Buenz, with Transsolar KlimaEngineering, and it is notable for its mechanical system which permits mixed-mode ventilation.
If external air temperatures cannot be used to heat or cool the Information Commons’ internal space to comfortable levels, an automated system automatically closes windows and the double-skin cavity walls. Internal systems kick in, and include radiant concrete ceilings for heating purposes, and mechanical under-floor air delivery for cooling and air circulation. Daylight sensors detect ambient light levels and dim the building’s fluorescent light when it is not required.
Canadian Examples of Net Zero Design
The Canadian Mortgage and Housing Corporation (CMHC) is promoting a prototype net zero house. The EQuilibrium house concept is being developed by a variety of builders. It uses alternate energy systems like solar panels and geothermal energy to diminish the building’s dependence on conventional energy sources. The CMHC is encouraging builders to adopt sustainable practices for disposing of construction waste and recycling materials.
At a larger scale, the City of Vancouver has developed sustainable design guidelines for the design and construction of Millennium Water, which will serve in the short term as Vancouver’s Olympic Village for the 2010 games. Passive energy strategies are an important aspect of the development, and include orienting buildings to take advantage of daylight and passive heating. Sophisticated natural ventilation and shading devices promote occupant comfort and reduce reliance on artificial cooling.
Canada’s first net zero multi-unit residential building, with support from the CMHC, will be located at the site. A district energy system will deliver about 60 percent of Southeast False Creek's energy needs. Smart utility monitoring and management devices in each unit will complement the long list of sustainable features, and add up to a sound business case for sustainable design.
Net Zero or Nearly So, and the Cost
By definition, a net zero building should generate as much energy as it consumes on a yearly basis. With the exception of one building, the bulk of the Millennium Water project will still require energy and contribute somewhat to CO2 emissions. The upside to designing sustainably on a large scale like the Vancouver site is that it is cheaper and more efficient to incorporate alternate energy systems and arrange for optimal building orientation to promote passive solar design.
The CMHC single-family residential unit typically costs an additional $60 per square foot, a significant increase for the average home owner. Small-scale design makes it harder to achieve net zero objectives at an affordable price.
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