Net Zero Performance + Design Strategies

The Joyce Centre for Partnership & Innovation at Mohawk College

December 21, 2017

Written by: Kevin Stelzer, Principal

By powering the building completely with electricity and generating the yearly total energy usage through its photovoltaic array, the Joyce Centre for Partnership & Innovation at Mohawk College will generate all the energy required to power its functioning through the course of the year – on site.

The projected energy intensity of the facility is 70.5 kWh/m2/annum (approximate to within 2.5%), which equates to an approximated annual consumption of 700,000 kWh (accounting for contingencies such as lab equipment, a targeted use of mechanical systems and an allowance for unregulated plug loads). During the longer summer daylight hours, the solar system will provide more energy than the building requires with the sun high in the sky. During the shorter winter months, energy production will generally be less than the building needs. The solar system will be optimized so that on an annual basis, actual energy production will slightly exceed predicted energy consumption. Because the mechanical design of the facility is demand operated, it will only operate when the facility is occupied.

Daylight and Lighting Systems

Daylighting elements include high-mounted daylighting fenestration above vision glazing in all laboratory and classroom spaces. While still providing diffuse light to the space, the daylighting will incorporate glare control elements.

Designed with the intent to utilize daylighting as a primary source of illumination, the electric lighting system controls will reduce electric light output when adequate daylight is available. Lighting will be switched off by control of occupancy sensors should the occupant neglect to shut the lights off manually.

HVAC Systems

The mechanical systems are being designed for efficiency using the following guiding principles:

  • Distributed heating and cooling to meet thermal loads
  • A dedicated outdoor air system to separate ventilation from heating & cooling
  • Allows for better comfort control by separating humidification control from space temperature control and increasing the effectiveness of exhaust air heat recovery
  • Heat pump-based heating to reduce on-site energy consumption and eliminate fossil fuel consumption
  • The heat pumps are coupled to a geoexchange well field, consisting of 27 wells, that will serve as the heat source/sink
  • Demand-responsive (CO2) systems for ventilation and heating/cooling

Water Conservation and Supply 

Potable water use reduction is one of the key sustainability objectives of this design. Strategies include:

  • Ultra-low flush urinals
  • Low flow faucets
  • Rooftop rainwater harvesting for toilet/urinal flushing and irrigation needs

Enclosure Performance

Taking a holistic approach to the building’s design, the windows, walls, and roofs were treated as a single system and were assigned an overall effective heat loss performance target. This target required the architecture team to focus not only on wall insulation and window U-values, but also the impact of glazing ratios on the whole building envelope heat loss. A very detailed analysis of the envelope assemblies ensued. For example, a high-performance unitized, triple glazed curtainwall system, augmented specifically for this project will employ rubber isolation gaskets between unit frames, which will ensure the lowest possible heat transmission. The system, among other innovative aspects, helps prevent flanking, which is when heat moves laterally between aluminum frames. Glazing units with multiple low-E coatings, ceramic frit, and argon fill will combine with a highly studied window-to-wall ratio to control solar loads – reducing cooling demand.

High Performance Envelope Design Details

  • Total envelope assembly thermal target: To increase the stability of the interior environment relative to the climate loads and ensure the HVAC systems work the minimal amount of time. The thermal performance of the facility has been designed to achieve an effective average value of RSI 1.76 W/m2/C (R10 btu/ft2/F).
  • Glazing is a unitized triple glazed aluminum system, with specialized framing and gasketing. All vision glazing targeted a thermal performance of Uvalue 0.8 W/m2/C (R7 imp).
  • In addition to the curtain wall, an insulated precast sandwich panel system was selected to assist the construction manager in accelerating the construction schedule. The panels have 100mm of encapsulated polyisocyanurate insulation with 75mm polyurethane spray insulation back-up. The system can be erected quickly, with excellent quality, and sealed from the interior for exceptional field value thermal performance.
  • Roofs are designed to a thermal performance of RSI 7.01 (R40 imp). The assembly is designed as a conventional system, comprised of 2-ply SBS Modified Bitumen membrane, polyisocyanurate insulation board, vapour barrier, on sloped structure and local tapered insulation board. The system will be cold applied adhered, with a high reflectivity top sheet.

Structural Framing & Special Structural Features

The building superstructure will be structural steel. Floor composition will be 90mm of concrete on 75mm steel deck for a total depth of 165mm. Steel beams will support the steel deck and concrete using composite action. The composite action and the use of dead load camber on the beams will minimize the depth of the beam required to carry the floor load and control deflection on the long spans. This will allow for maximum open space and future flexibility.

The solar Photovoltaic support system will be a combination of structural steel and proprietary supports by the solar panel fabricator. To maximize the area of the solar collection, a unique design for the solar farm will span across the building in the East/West direction. The wing-shaped structures will be supported on a series of uniquely designed steel sections. These sections will be fully exposed and will add a unique aspect and teaching potential.