Village Suites Oshawa is a 556-bed student residence built for the University Of Ontario Institute Of Technology, Canada’s fastest growing university. The building is currently being evaluated by the CaGBC for LEED Platinum certification and if successful, at 270,000 square feet will be one of the largest LEED Platinum certified buildings in Canada.
The Village Suites’ high-performance building envelope derives its thermal performance from a variety of elements and illustrates a number of important scientific building principles.
Thermal performance through enhanced R valueThe high performance envelope is built with an insulated concrete forms system. The foam insulation in the Logix Platinum Series walls is provided by Neopor, which was patented by BASF in 1995 and currently carries the McDonough Braungart’s C2C (Cradle to Cradle) service mark. Used extensively in Europe and Asia for many years, Neopor is quickly gaining market acceptance in North America.
Neopor is an expanded polystyrene product that is performance-enhanced by millions of graphite particles that act as infrared absorbers and heat reflectors. Neopor is different from regular EPS in its look, which is silver/gray, and its thermal performance, which is roughly 13 percent greater than a regular Type II EPS. Regular Type II EPS provides an R value of about 4.0 per inch at 75 degrees and Neopor delivers an R value of about 4.7 per inch at that same temperature. Thus Neopor provides greater R value than normal EPS without increasing wall thickness.
The interior and exterior neopor-enhanced Logix Platinum Series foam panels are each 2.75 inches thick for a total of 5.5 inches of foam insulation in the wall. At an R value of 4.7 per inch, the R value delivered by the foam insulation is 25.8. When the R value of the drywall and air films is added, the R value of the Logix wall assembly comes in at 27.
It is important to note that in this ICF wall assembly the insulation is continuous. Therefore, any thermal bridging and resultant heat loss through framing members is completely eliminated.
Air tight and foolproofAir leakage, or the unintended movement of air across the thermal boundary, generally contributes to the majority of energy loss in conventional framed construction. Air can transfer heat and moisture not only through the envelope, but in the case of framed construction it may enter into the cavity wall-introducing a conductive current which decreases the thermal value of the insulation.
Sealing air leaks can be very complicated. Building paper and spray or blown insulation may help seal some gaps initially, but complete air sealing requires additional detailing of gaskets and sealers at the sill plates and continuous attention to repair holes made by tradesman. This adds a layer of complexity to the building process and requires a level of attention to detail which is difficult to achieve on most construction sites.
Also, the points of air penetration in a framed wall cavity, such as sheathing joints, floor/wall joints and insulation gaps only get worse over time as the framing shifts. Air barriers joints and seams also need to withstand positive or negative pressures from wind, stack effect and mechanical ventilation. Sealants at the time of construction only provide minimum protection against future air leaks.
The best defense against air leaks is to build with a material which by its very composition has no air leakage independent of the skill of the workforce. This is the case with the concrete core of the Logix wall. As the ready-mixed concrete is placed on site, it forms a monolithic concrete wall which is virtually air tight. Penetrations in the wall, such as windows, doors or utility service pipes are clearly identifiable and can be sealed for air tightness.
The Canadian Mortgage and Housing Corporation quantified the additional thermal performance provided by the air tightness of ICF technology in the 2005 study titled “Monitored Thermal Performance of ICF Walls in MURB’s.”
In this study, they monitored a building quite similar to Village Suites and concluded, “The results from this test suggest that the design heating and cooling loads and subsequent sizing of the building’s heating and cooling system may be based upon an air infiltration rate that is up to 60 percent lower than standard construction.”
Thermal mass and youHigh mass wall structures such as concrete have the added benefit of increasing the energy performance of a building despite having a low R value. Concrete can provide a thermal lag as it absorbs the temperature differential between the indoor and outdoor temperatures. This property of concrete is known as the “thermal mass effect.”
The thermal mass effect is influenced by differences between the indoor and outdoor temperatures. Since heat flows naturally from a warmer place to a cooler place, two scenarios can affect the mass effect of concrete:
- Outdoor temperatures which fall above and then below indoor temperatures, and
- Moderate climates and the transitional periods between the heating and cooling seasons.
This study concluded that ICF thermal mass provides a five-day thermal lag which contributes energy savings to the building above and beyond the R value of the assembly. This study also supports previous CMHC research which has shown that the thermal mass effect in ICF walls can be used to downsize the mechanical systems.
Completing the high-performance envelopeThe concrete deck roof is coated with a white-colored, highly-reflective, polyester-reinforced membrane to reduce the amount of radiant heat absorbed into the building and minimize the amount of energy needed to cool the upper floors in the summer months.
Double glazed, low-e argon windows were used to reduce solar heat gain. The window openings were designed, sized and placed to permit natural daylight to reach 75 percent of the interior spaces.
Augmenting the high-performance envelopeERV units were installed in each unit to maximize indoor air quality and to recover up to 70 percent of the heat of the exhausted air. Also, a watt meter was installed in each unit to monitor energy consumption.
Evacuated heat pipe solar panels were installed on the roof to heat water via sunlight. Additionally, a photovoltaic panel array was installed to take advantage of the Ontario Green Energy Act. Finally, Village Suites has committed to purchase 50 percent of contracted energy requirements from renewable sources such as solar-, wind- and water-generated sources.
The bottom (energy) lineDesign modeling projects a 75 percent reduction in heating and cooling costs and a 50 percent reduction in electricity usage as compared to a building built to prevailing minimum building codes. The development is a notable achievement in building science and a job well done by the design and construction team at Village Suites.
Project NotesProject: Village Suites Oshawa, Oshawa, Ontario
Status: In evaluation for LEED Platinum
Square Feet: 270,000
Production Dates: August 2009-October 2010
Project Cost: $35 million
Owner: DC Land Corp
Architect: Lintack Architects Inc.
Structural Engineer: MTE Consultants Inc.
General Contractor: Dundurn Edge Developments Inc.
ICF Installer: Tradewind Construction
ICF Supplier: Logix Insulated Concrete Forms Ltd.