Ventilation and Overheating in 1970s Low-Rise MURBs – A Case Study Modeling

Alireza Asharioun, M.Eng, CPHD, EIT
Senior Technical Researcher, BC Housing

Alireza Asharioun is a building science engineer with a rich building and mechanical systems background. His expertise covers building enclosure, energy performance, indoor environment quality, and building decarbonization. Committed to Equity, Diversity, and Inclusion (EDI) principles, Alireza values diverse perspectives and contributes as a collaborative team member to innovate in building science. Skilled in software like PHPP, WUFI, and Sketchup, Alireza optimizes building performance, ensuring sustainable and inclusive design solutions. As a Senior Technical Researcher at BC Housing's Research Centre, Alireza elevates residential construction standards and aids in affordable housing solutions. As a part-time-study faculty at BCIT, Alireza supports the Building Science master’s program. With a master’s in building science from BCIT and a bachelor of mechanical engineering degree from Montazeri Technical College, Alireza holds a Certified Passive House Designer (CPHD) certificate and is registered as an Engineer-in-Training with Engineers and Geoscientists BC.

Multi-Unit Residential Buildings (MURBs) constructed in the 1970s were designed to suit the climate conditions prevalent during that era. These buildings were initially designed to rely on natural ventilation and cooling by opening windows during cooler night temperatures, storing this coolness in the building's mass for the next day. However, due to climate change and rising summer temperatures and heatwave events, nights are no longer sufficiently cool to offset daytime overheating, leading to uncomfortable living conditions. A 2018 BC Hydro report revealed that over 60% of BC buildings lack mechanical air conditioning. Climate change further exacerbates the ventilation issue with increased wildfire events, reducing air quality and limiting window ventilation. Alongside overheating, these MURBs face challenges like poor indoor air quality, noise issues, and high energy consumption. Given BC's climate goals, there is a push towards energy-efficient retrofits for existing buildings, particularly older MURBs. Evaluating the current conditions across mechanical systems, building envelope, electrical capacity, energy sources, and Indoor Environmental Quality (IEQ) is crucial. The aim is to balance energy efficiency and GHG reduction with residents' health and comfort in mind. This presentation elaborates on the results of a case study of 1970s low-rise MURBs and the solutions recommended for retrofitting such buildings.