1:20 pm - 2:30 pm | Room: Pretium Room | Session Chair: Negar Pakzadian

Building Performance Modelling

The Role Of Thermal And Hygrothermal Modelling In Deep Energy Retrofit Of Heritage Buildings

As Canada begins to reduce carbon emissions to meet climate change mitigation targets there is a growing need to retrofit existing building stock, especially heritage buildings of cultural significance. Retrofitting existing buildings has many inherent challenges including, costs, existing building design, and current building condition. In addition to those challenges, practitioners working on deep energy retrofits of heritage buildings must also balance the need to improve energy performance and occupant comfort while preserving the historic value of the building through minimizing any alterations to the building façade. A popular strategy to meet these objectives is to add insulation on the interior side of the existing assemblies. However, adding interior insulation presents many challenges, including durability risks from altering the heat and moisture flow through the assemblies and difficulty in mitigating heat loss through thermal bridging to improve building envelope thermal performance.
This paper discusses the role of thermal and hygrothermal simulations in improving the thermal performance and durability of building envelope upgrades for heritage masonry buildings and presents an approach where to effectively use these models. The approach includes the use of 3D thermal analysis to evaluate thermal bridging at critical details including window to wall details, intermediate floor, and parapets. Results from these models provide a better understanding of the complex heat flow paths leading to more effective thermal bridging mitigation strategies including the use of innovative materials such as aerogel insulation. 1D and 2D hygrothermal analysis was used to evaluate heat and moisture flow of existing and retrofit wall assemblies to better assess the risk of freeze-thaw damage. The analysis evaluated wall sections that included stone masonry and mortar joints. Findings from the thermal and hygrothermal analysis help guide designers in developing appropriate design options to reduce the carbon emission of the heritage building. These design options can then be evaluated in whole building energy models to better quantify energy consumption and carbon emissions reductions.

Ivan Lee, Morrison Hershfield

Ivan Lee, P.Eng., M.A.Sc., LEED AP^BD+C is a Building Science Consultant and Team Lead of the component modelling group in the Building Performance Analysis department with a focus on thermal analysis, hygrothermal analysis, and Life Cycle Analysis. Ivan graduated from the University of Waterloo in 2010 and has worked at Morrison Hershfield for over 12 years. He has been involved with various past projects including 3D thermal modelling to assess thermal bridging details for the Building Envelope Thermal Bridging Guide (BETB Guide), and the Guide to Low Thermal Energy Demand for Large Buildings (Low TEDI Guide), as well as condensation analysis of window wall and curtain wall glazing systems.  Ivan also has experience in hygrothermal modelling of building envelope assemblies including research in hygrothermal performance of framed wall assemblies and details with vapour permeable membranes and determining risk of freeze-thaw damage in masonry.