By Christopher Piché, P.Eng., Integral Group
Teaching in Green: Elementary Teachers’ Federation of Ontario HQBuildings Energy Efficiency/Conservation Environmental Consulting & Engineering green buildings
The award-winning Elementary Teachers' Federation of Ontario Headquarters in downtown Toronto combines passive and active energy saving measures to achieve over 55% savings.
From the May 2015 print issue, page 16
The goal of the 11,400 m² Elementary Teachers Federation of Ontario Headquarters is to become a leader not only in education but also in environmental protection. The four-storey building at Bloor and Jarvis Streets in downtown Toronto demonstrates how innovative sustainable design can be successfully integrated into an urban neighborhood in transition. It is also a candidate for LEED Platinum certification.
Integral Group provided mechanical engineering consulting services as part of a comprehensive design team led by Kuwabara Payne McKenna Blumberg Architects. Integral Group won an Award of Excellence in the 2014 Ontario Consulting Engineering Awards in the small firm category for their role in the project.
Throughout all the design phases an integrated design process was used that involved all consultants at all design phases. Also a Guiding Charter was established that allowed the team continually to assess sustainability measures against the client’s objectives.
The result was a building completed in 2013 that combines proven passive measures for sustainable design coupled with active high performance technologies. It will have an estimated 64% of energy cost savings compared to the Model National Energy Code for Buildings (MNECB).
First the team focused on optimizing all passive sustainable design components before integrating active technologies. We relied on a comprehensive building energy model to analyze each technology in extensive detail and subsequently optimize their integration.
Daylighting and solar control
Each of the four floors is wrapped around a large atrium that is strategically placed at the centre of the building. As a result daylight can penetrate deep within each floor plate without the ceiling levels having to be raised significantly. The atrium also serves as an anchor and way-finding point for people as they navigate through the building.
Daylight and occupancy sensors help to manage the harvesting of daylight to reduce the lighting energy demand. North facing skylights also make the building feel fresh and vibrant by creating another connection to the outdoor environment.
Along the south and west facades there is exterior solar shading, which operates automatically based on daylight levels measured at the exterior. Locating the shades on the exterior means that solar heat can’t enter the building then remain trapped within an enclosed space between blinds and windows.
Geo-exchange field installed after structural slabs
The building’s heating and cooling needs are served by a geo-exchange field that is located directly below the building. While the installation of a geo-exchange field traditionally occurs before any structure is installed, in this case the team installed 85 boreholes, each at a depth of 500 feet, after the structural slabs had been installed and the shoring was removed.
The technology used for drilling the boreholes is based on mining technology. The equipment was anchored temporarily to the structure and then used to drill boreholes in 4-ft. spools. As a result, the project could proceed on a traditional construction schedule without the delay of “waiting” for the borehole field to be drilled. Using this technology, the installing contractor drilled three to four holes per week, while construction of the superstructure was able to continue simultaneously and uninterrupted. The process shaved three to four months off the overall construction schedule, minimized disruption to the surrounding neighbourhood from drilling, while providing a higher performance system.
Every ounce of energy
The building aspires to use every ounce of energy created before it leaves the building.
The efficiency of the heat pump system is the main driver for energy savings, along with the decoupling of the ventilation systems (outdoor air) from the thermal loads (heating and cooling). The thermal loads are provided by hydronic means – a much more effective system vsersus an all air system.
In the summer months, the geo-exchange field is the primary source of cooling. The cooling is provided to a series of radiant ceiling mats, and heat is rejected to the field through four high efficiency extended range heat pumps. During the shoulder and winter seasons, the building systems recover and transfer waste energy generated in the building before using the energy stored within the field:
A dedicated heat exchanger is installed between the geo-exchange field and the building. In the winter, the loop provides cool water from the central heat pumps to the interior zones first; these zones essentially require cooling year round. The loop, having picked up heat from the interior zones, is then routed towards the perimeter zone, thus effectively “transfering” the energy. This represents the first stage of heating.
If the building requires supplemental heating, energy is recovered from the general and washroom exhaust systems, and transferred to the hydronic loop to supplement heating demand. This represents the second stage of heating.
Finally, if the building still requires more heating, then the heat pumps will engage and provide low grade heating from the field to the overall radiant ceiling system.
The building is controlled via a central building automation system which monitors control points such as temperature, humidity and indoor air quality (CO2) to enable the various systems to respond to indoor environmental demands.
The building energy use intensity (EUI) is 113 ekWh/m² excluding the parking. Each of the heat pumps is rated for 45 ton capacity and the air-handling units are providing only ventilation air to the building — hence the fans and corresponding ductwork are much smaller than a conventional all-air system (approximately 30% of the size required for all-air). Each pump is selected with premium efficiency motors, and variable speed drives are incorporated where suitable.
There is also a green roof and rainwater is captured on site and re-used for water closets and urinals.
Window-to-wall ratios of around 40% were chosen, which mitigates the heat island effect, thereby positively affecting energy performance.
Finally, the design team developed a comprehensive measurement and verification methodology to validate the design analysis and overall performance. The anticipated design-based performance metrics include the following:
• conditioned space of 8,049 m² (11,500 m² total)
• energy intensity (building and processs): 112 ekWh/m²/year
• energy savings (ekWh): 55.7% reduction over MNECB reference model
• energy cost savings ($): 64% reduction over MNECB reference model
• in-building potable water use reduction: 50%.
ETFO acquired the two-acre site, located within a well established and highly dense neighbourhood, in 2007. The urban nature of the project added to its complexity. Community engagement was a priority from the outset and meetings led to a number of measures that enabled the design team to deliver a building that integrates with ease into the existing fabric of the neighbourhood. For example:
• The team analyzed the building sight lines and aspect ratios to maximize daylight penetration and access to views. At the same time we ensured that unnecessary shadows were not cast on surrounding buildings.
• The team selected a colour scheme and brick colored panels that blend with the surrounding buildings and neighbourhood context.
The new headquarters provides teaching professionals and educational workers with a healthy, comfortable and collaborative environment. At the same time it shows that we can ask for buildings that in terms of sustainable performance go far beyond what we see in the typical commercial office building. cce
Owner: Elementary Teachers’ Federation of Ontario
Mechanical engineer: Integral Group
(Chris Piché, P.Eng., Jeff Phinney)
Structural engineer: Blackwell
Electrical engineer: Smith & Andersen Computer modelling: CDML/Integral
General contractor: Bird Construction
Other key players: CFMS West (commissioning), Turner Townsend (client representative), Fenix Energy (geo-exchange installation)