Energy Efficiency of Below-Grade Building Envelope

Energy Efficiency of Below-Grade Building Envelopes in Cold Region

RAKirill Bobko (MSc Student)

Project Duration: 2016 – 2018

Collaborators & Partnerships:

Financial Support:

Project Description: 

A significant component of total global energy demand relates to energy used to heat and cool buildings. In Canada in 2009, 63% of all residential energy use was for space heating. To date, most efforts to decrease the energy loss in buildings have been concentrated primarily on the above-grade envelope of buildings such as walls and roofs, since they initially posed the largest potential. However, it is also recognized that significant heat losses may occur due to the flow of heat from the inside of a building through the ground floor slab and into the foundation soils. For example, it is estimated that 10 to 40% of heat loss of a residential building occurs through its foundation (Federal). As some parts of the basements are located above ground, one can assume that 75% of heat loss occurs through the basement structure.

One of the most significant factors, which influence heat transfer in the ground is moisture content. Moisture content might increase effective thermal conductivity by a factor of ten. That is why for those calculations where moisture content is taken as constant the error can be significant. Temperature changes generated in surrounding soils by heat losses from the basement to the ground may result in strongly-coupled, nonlinear moisture and energy flow. Cold climates may lead to freezing of pore-water in soil near the ground surface. Freezing involves temperature gradients and moisture migration due to cryo-suction. This phenomenon, with or without frost heaving, has significant consequences in foundation engineering in areas of both seasonal frost and permafrost. Despite its importance, the impact of phase change between water and ice (freezing/thawing) on the thermo-hydraulic regime of unsaturated soils surrounding building foundations is not well known.

This research study aims at studying the energy performance of below-grade building envelopes as well as crawl spaces in residential and institutional buildings across Manitoba, particularly in remote communities. A comprehensive framework will be developed to 1) Investigate the energy performance of basements and crawl spaces of some typical buildings (residential and institutional) by using a sensing monitoring system (temperature, humidity, heat flux); 2) Calibrate the coupled Thermo-Hydraulic numerical model developed by Dr. Maghoul by using the field measurement data; 3) Determine the most energy-efficient configuration of insulation around the basement structures by performing numerical analysis; 4) Construct a pilot building on campus of the University of Manitoba (Smart Park) to validate the numerical predictions.

The ultimate goal of this study is to identify the design criteria that could efficiently and economically be incorporated to improve the energy performance of residential and institutional buildings for geological and climatological conditions in remote areas.

Outcomes:

Bobko K., Maghoul P., 2018. Energy Performance of Stanley-Pauley Building in Winnipeg, Building and Environment, In preparation.

Bobko K., Maghoul P., Kavgic M., 2018. Energy Performance of Below-Grade Envelope of Stanley-Pauley Building in Winnipeg, 71th Canadian Geotechnical Conference (GeoEdmonton 2018), Edmonton, Canada.

Maghoul P., Kavgic M., and Bobko K., 2017. Modeling of Thermal Performance of Foundation Walls in a Cold Climate, 70th Canadian Geotechnical Conference (GeoOttawa 2017), Ottawa, Canada.