OAA HQ is a public and physical embodiment of an architect's skill and aspirations to the community, as well as serving needs for office space.
Given society's current focus on energy efficiency and the movement towards public declaration of energy use that is sweeping across the USA, the OAA asked itself how its building would perform. The answer: not very well.
One solution would be to scrap the building and start again, but aside from being financially imprudent, most building stock is intended to serve for much longer than 20 years, and buildings need to adapt and improve with time. The OAA HQ is no different.
The OAA has committed to the 2030 Challenge as a general policy. This challenge aims to take the building sector to zero carbon emissions by 2030. Its strategy is to set performance targets for all new buildings and major renovations. The target energy use for all buildings completed in a given year is slowly being reduced from the average levels achieved in 2003. Next year, that target will be 70% of the baseline; by 2030 the target will be 100% reduction.
The OAA could meet the 70% reduction rate, but asked itself wheter it could take a leadership position and meet the 100% reduction target. This would generate confidence in the industry. It would provide a strong example that the profession, and future professionals through the use of the OAA HQ in teaching curriculums, could use in their own work. Council also felt that the carbon neutral renovation had education value for the public, members and students.
The OAA building does provide energy challenges. The first floor is open and the building has thermal bridging. Instead of viewing these as impossible challenges, our consultant team David Fujiwara Architect with Sustainable EDGE, Gottesman Associates and Transsolar decided to work with the strengths and opportunities inherent in the building form-- including, ironically, the open space on the first floor.
The first advantage is that the building has fantastic daylighting that is currently duplicated with artificial lighting. Deborah Gottesman has designed a system which will replace existing lighting with high efficiency lighting, using a daylight strategy to turn off lighting when sufficient daylight exists, while using new fixtures that complement the building's style.
Its second advantage is the atrium which allows us to optimize displacement ventilation, using a similar strategy to that used at the Manitoba Hydro Place
. This system has significant energy savings because of the low fan energy required.
A third advantage is that the building was originally designed to support shading devices on the roof fins. These were never installed due to cost (having a payback of 20 years!). Our daylighting study
has concluded that there is so much daylight in the building that glare control is required. The project proposes to use photovoltaic/hydro thermal panels to perform this glare control, in addition to adding external shades to the building.
The first step will be envelope upgrades to reduce the heating and cooling loads. According to a blower door test, the OAA building envelope scores very well for air tightness, which is a major source of energy loss. However, there are some improvements to be made, and insulation can be added to further reduce the loads.
The mechanical system is next. The current mechanical system, whose goal was to maximize user comfort, uses forced air heating augmented with reheat coils in each VAV box, and electric base board heaters. In cooling mode, the system cools air to 13 degrees, and then reheats the air for each individual office. While this strategy was considered a good one when the building was built, it consumes a lot of energy. After 20 years of service, many of its components are coming to the end of their life expectancy.
The OAA is proposing to entirely re-work the mechanical system, changing it to a displacement system which takes advantage of the atrium as a supply plenum, and adding an energy recovery ventilator. The only part of the system to be retained are the supply ducts, which will be reused as return ducts.
The system will be driven by photovoltaics with an integral hydro thermal system, made more efficient through the use of underground storage tanks to both store heat and absorb heat from the ground.
Finally, the building’s interiors are somewhat worn and the creation of a more functional atrium space, work spaces and meeting/collaborative spaces will be addressed, with updated finishes throughout.
In 2008, Council commissioned a study by Cushman and Wakefield to determine, from a financial view only, if it made sense to sell the building. They determined that it did not. View study here.
Having decided to keep the building, the next issue to be addressed was the maintenance of our existing system including replacement of components as they reach end of life. This had an estimated cost of $1.3 million over the next 10 years, including the leasable office expansion.
The system described above is estimated to cost $3.8 million, also including the leasable office expansion.
However, the OAA currently pays $90,000 per year in energy bills and $27,000 in maintenance costs. When this is taken into account though a Net Present Value analysis, the results suggest that the zero operating carbon renovation is the most financially attractive over the 25 year term. A summary of this analysis is below. The complete report is available here.
The NPV analysis is based on a conservative estimate of future energy costs, and on the OAA current rate of return on investments (2%). This yields a payback of 17 years. If more drastic energy scenarios are used, the payback is reduced to as low as 7.5 years.
The Association has sufficient resources to pay for the renovation over a four-year period, without increasing member fees. This is in part due to the fact that the OAA has paid off the mortgage. However, we may choose to enter into an agreement with an organisation like the Toronto Atmospheric Fund, which pays qualifying capital costs in exchange for receiving most of the energy savings over a defined period.
Council approved the Carbon Neutral retrofit on March 6, 2014, for a maximum cost of $3.8 million and directed the team to proceed through design development and working drawings. At that point, performance and costs must be confirmed.
The project was presented at the 2014 OAA Annual Conference during the Friday lunch hour.