BUILDING RESEARCH

Addressing Energy Efficiency
The latest housing research from NRC

By Brad Gover

Jointly operated by the National Research Council (NRC), Natural Resources Canada and the Canada Mortgage and Housing Corporation, the Canadian Centre for Housing Technology (CCHT) was designed to provide manufacturers and product developers with a real-world test environment for assessing innovative technologies prior to full field trials in occupied houses.

The National Research Council (NRC) has a long history of supporting Canadian home builders and the construction industry. NRC probes issues and demonstrates new technologies that advance home building and open new markets in response to industry needs. Recent projects related to building envelopes include enhanced interior insulation and new roofing solar technology. As well, a project on wood-based structural products for mid-rise buildings will help builders make further strides in improving the efficiency and comfort of mid-rise buildings.

Interior and Exterior Insulation
To build more energy-efficient homes, builders and manufacturers have been enhancing interior and exterior insulation. But could higher levels of insulation in wall assemblies result in condensation and moisture problems? To determine the effect of enhanced insulation on wall performance in houses, NRC partnered with the housing industry, the Canadian Mortgage and Housing Corporation (CMHC) and Natural Resources Canada (NRCan).
The project involves testing building envelope retrofit strategies and new construction for heat, air and moisture performance with conventional wood-framed walls. Three retrofit strategies using different types of insulation were set up in a full-scale field exposure of walls facility.
Although testing is being conducted in Ottawa, NRC used a model to simulate the response of the retrofit strategies to the indoor and outdoor conditions of different climatic regions of Canada. These results will be compared to those of the insulation levels that comply with wall assemblies from the 2011 National Energy Code for Buildings. The findings will help builders determine the best insulation level for their building projects.

PV Technologies
Increasingly, Canadian homeowners are asking for photovoltaic (PV) technologies that are durable and cost-efficient, and can withstand Canadian weather. In response, NRC is testing new solar photovoltaic (PV) technologies.
To test the energy yield of new micro-inverters in steep slope roofing applications, NRC set up two side-by-side PV arrays on a test rig simulating an 18-inch steep sloped roof, with one using new micro-inverter technology and the other using a standard string inverter. Shading conditions experienced by a typical Canadian residential rooftop were applied to test the relative performance of the two arrays.
The micro-inverter was found to increase production by 10 to 50 per cent compared to the string inverter. The project also investigated the interaction of the PV systems with the roofing system in terms of heat and moisture performance, and the impact of snow cover on the energy yield of these PV systems. Results from this project and others, help consumers and builders chose the best type of PV for their homes.

Wood Buildings
With Canada on track to become one of the largest construction markets in the world by 2020, demand for wood buildings continues to increase. In collaboration with the Canadian Wood Council and FPInnovations and in partnership with NRCan and the governments of Ontario, Quebec and British Columbia, a comprehensive study on the use of wood-based structural products in mid-rise buildings (up to six storeys) was undertaken. NRC is developing solutions to meet code objectives in key areas including fire safety, acoustical quality and building envelope performance. A particular objective of the project is to ensure that specific technical solutions developed to address one aspect of building performance (such as fire protection) do not have a negative effect on other aspects (such as acoustics or moisture protection).

Sharing Research Results
Results of these three projects and others we are working on will be available through a number of venues. NRC produces a variety of publications outlining its work. Its Construction Innovation publication is published quarterly, and contains the latest news on projects and codes development. NRC also publishes Construction Technology Updates regularly on their website that includes practical, technical details on its research for builders. NRC also produces an annual Housing Report, in conjunction with CHBA, to summarize the previous year's work and provide updates and results. NRC's experts also share their knowledge and research results at conferences and tradeshows across Canada.
In addition to its ongoing research, NRC evaluates and provides technical expertise for building technologies and products through the Canadian Construction Materials Centre (CCMC). To help industry become more innovative and competitive, CCMC demonstrates the performance of innovative and cost-effective products and solutions.
To learn more, and to access NRC publications, visit www.nrc.gc.ca.

Dr. Brad Gover is Director of the Building Envelope and Materials program at NRC Construction and leads another program that supports commercialization of innovative building products, and delivers efficient and uniform building codes.

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