Quantifying air leakage through party walls in Toronto semidetached and row-home dwellings

Austin Todd

doi:10.32920/ryerson.14657412

Abstract

This study contributes to the development of quantifying and understanding building air tightness as it relates to Toronto semi-detached and row homes, particularly party walls. While infiltration characteristics of single family detached homes have been widely developed and understood, the isolation of semi-detached and row home single family dwelling units is relatively unexplored. When quantifying air leakage in a building attached to an adjacent dwelling unit, air is drawn through the exterior envelope as well as the party wall (i.e. shared common wall). The purpose of the proposed testing method, guarded blower door testing, is to isolate air leakage through the party wall from the envelope. Currently the party wall is considered a fire-rated assembly but is not part of the air barrier system. Issues associated with party wall air leakage include spread of fire, indoor air quality, transfer of tobacco smoke between dwellings, and heat loss through the party to attic detail. Data collected on buildings constructed between 1890 and 1920 (Century buildings) has been compared to the data collected on buildings constructed between 2012 to 2017 (new buildings). Air leakage has been collected on twenty-six of Century semi-detached homes with solid masonry construction and twenty-one new semi-detached/row homes of lightweight wood frame construction. Each unit was tested independently and simultaneously, or “guarded”, with the adjacent unit, to pressure neutralize allowing for quantification of envelope and party wall air leakage. Party wall leakage was found to be similar to leakage through the exterior walls. The leakage accounted for 22% of the total infiltration in Century old buildings and 38% in Modern dwellings.

Highlights

Four major components can be identified in residential homes: weather barrier, thermal barrier, air barrier, vapour barrier; all of which are components of the building envelope
This study focuses on quantifying air leakage through the party wall of Century semidetached homes as well as Modern semi-detached and row homes to understand the dwellings air leakage characteristics, as well as quantify party wall air leakage, through the use of an experimental testing method
Building air leakage through the exterior is associated with the energy required to condition the uncontrolled infiltrating air whereas air leakage through party walls is associated with occupant health and comfort

Summary

Introduction

Four major components can be identified in residential homes: weather barrier, thermal barrier, air barrier, vapour barrier; all of which are components of the building envelope. When looking at a multi-unit residential building (MURB), the dwelling is only partially exposed to the exterior environment and a new main component is introduced; a fire barrier; under the Ontario Building Code this wall is referred to as a party wall. This is a physical separation between two dwelling units that is intended to mitigate the spread of smoke and fire within a dwelling. Air leakage through the envelope has a direct energy cost because in a mixed climate with harsh conditions the infiltration air often needs to be conditioned, increasing the load on mechanical systems. With heightening environmental concerns, such as climate change and aging energy infrastructure, the Building Code is being used as a tool to set higher building standards to minimize energy consumption

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