Should Net Zero be Today’s Goal?
Net Zero is the latest buzzword around the green building industry. The implication is that we should strive for buildings that consume no energy. The Living Building Challenge has set this target and the 2030 Challenge aims for zero carbon emissions from buildings by 2030. But is this the right end goal? While achieving Net Zero is laudable, it may be unrealistic for most individual Canadian buildings without significant capital investment in on-site renewable energy generation. Furthermore, it assumes the building is an island, ignoring its interaction with the rest of the city. Does a net zero building in suburbia, where everyone has to drive to work, truly have a net zero impact?
Perhaps a more practical goal is to get all buildings to be Net Zero Ready. Net Zero Ready buildings have energy demands so low that all of their remaining energy use can be feasibly supplied by renewable energy either at the building or community level or through waste energy from adjacent buildings.
What is the energy target for these buildings and how do we get this performance?
Currently the average Canadian commercial/institutional building uses close to 400 ekWh/m2 on an annual basis. Schools, offices and MURBs are on the low side of this number while hospitals, sports facilities and retail centres are on the high side.
Enermodal recently certified its 100th LEED project. Looking at back, we discovered that the monitored (actual) energy use of our LEED projects is 45 per cent less than the Canadian average, or just over 200 ekWh/m2. For the most part, these savings were achieved by focusing on a few critical areas: airtight envelope, efficient lighting, and high performance mechanical equipment including ventilation heat recovery.
But 200 ekWh/m2 is just the average. What about the best of the best performing buildings from an energy perspective?
The top 10 Enermodal LEED buildings were modelled to achieve (and did achieve) around 100 ekWh/m2, half of the average of the LEED buildings and a quarter of the ‘norm.’ To toot our horn for a moment, eight of the top 10 buildings were designed by Enermodal’s mechanical/electrical design group (but that’s not really the point of this article).
How to get under 100
What set these buildings up to be great energy performers? Three words: elegantly simple design. The old ‘keep it simple’ adage holds true. The problem is that it is extremely hard to do simple designs. Engineers are prone to over-sizing equipment, adding unnecessary control complexity, and using old rules of thumb that were developed when energy use was not a priority.
To achieve designs below 100 kWh/m2 requires a complete re-think about how we design buildings. And not just M/E design but architectural as well: proper orientation, narrow floor-plates, optimum window-to-wall ratio are all important. We did this in our new headquarters, A Grander View, which is running at 69 kWh/m2. For the record, it cost us around $250 per square foot to build and fit-up.
It is interesting to note that in the fine print of the 2030 Challenge, that program allows for 20 per cent of energy to be from green energy purchases. In other words, the actual building energy consumption needs to be 20 per cent of current values or 80 ekWh/m2 — pretty close to the 100 noted above.
While zero may be the ultimate goal, we believe that the technical and economically feasible target for buildings today should be 100 ekWh/m2. This is attainable. This helps renewable energy make economic sense. This affords opportunities to look at the interaction of building energy use on a community scale, instead as energy islands.
100 ekWh/m2 is no less an accomplishment than zero: only a handful of buildings in Canada have achieved this level of performance. At Enermodal we call this Net Zero Ready and all of our groups are working together to deliver projects at this level. We encourage the entire building design and construction industry to strive for this target, as well.