Thermal Performance Patterns on Solid Masonry Exterior Walls of Historic Buildings

Abstract

The Parliamentary Precinct in Ottawa, Canada, is comprised of a number of historic buildings that include the House of Commons, the Senate Chamber, the Parliamentary Library, the Peace Tower, and other buildings that provide offices for parliamentarians and their staff. The majority of these buildings have exterior walls that are made of solid masonry with thicknesses ranging between 400 mm and 800 mm. In some cases, special wall areas are more than 1200 mm thick and are comprised of various types of masonry materials. With winter design temperatures of-25°C, more than 170 cm of snowfall, and numerous thaws during the five month heating season, the exterior environmental conditions acting on the exterior wall assemblies of these historic buildings are severe enough to cause masonry and mortar deterioration wherever moisture accumulates during winter months.Infrared thermographic inspections were carried out to locate and identify the causal mechanisms of moisture accumulation within masonry wall assemblies. This paper will discuss the types of thermal patterns produced by various mechanisms of heat loss and identify some of the typical areas where possible masonry deterioration occurs. Knowledge gained from these extensive investigations will be used to develop a nondestructive test methodology to locate areas of freeze-thaw damage as part of a predictive and preventive maintenance program to reduce preservation costs of these historical structures.

Nondestructive testing and damage assessment of masonry structures

“…In a state of heat flux, differences in surface temperature will exist in the vicinity of materials with different densities, heat capacities, and/or thermal conductivities; these variations in surface temperature are measured with special cameras sensitive in the infrared range 0.76–30 μm. Originally developed by the military in the 1960s, in recent years infrared thermography has seen wide application to evaluating features of masonry building envelopes24, including: subsurface anomalies such as voids, near‐surface cracks, or incipient spalls; variations in wall construction; missing or displaced wall insulation; moisture rise by capillary action25; air leakage and variations in moisture content26; features hidden by surface plaster or frescoes, such as blocked openings or previous repairs18; internal cavities such as flues, ducts, or chimneys; the presence of grouted cells in reinforced masonry construction27, 28; thermal bridging of mortar obstructions in wall drainage cavities. …”

“…Interpretation of infrared images relies on interpretation by the user to determine the meaning of temperature anomalies. Operator experience is essential as well as an understanding of the physics behind heat transfer processes and the performance of masonry wall assemblies26. Under different heating and cooling conditions, for example, sections containing internal voids may show as either warmer or cooler regions.…”

Laboratory dilatometry and field test to assess durability of masonry

“…In Toronto (Canada) and many other cities with historic clay brick masonry buildings, concerns with energy efficiency of buildings coupled with an increased expectation of thermal comfort are resulting in a rise of internally insulated solid brick masonry buildings (Colantonio, 1997; Uranjek and Bokan-Bosiljkov, 2015). As past research has shown, insulating brick on the interior alters the historical hygrothermal regime and can result in increased freeze–thaw cycles, increased moisture storage and deterioration (Anderson, 1999; Delghust et al, 2010; Finch et al, 2007; Hutcheon and Handegord, 1995; Johansson et al, 2014; Klõšeiko et al, 2003; Künzel, 1998; Straube and Burnett, 2005; Straube and Schumacher, 2007; Wilkinson et al, 2009).…”

Computational justification for engineering measures preventing the ice dams formation on the pitched roofs

“…Особенно сильно подвержены такому негативному явлению чердачные крыши зданий со скатной кровлей. Данному вопросу и способам его решения посвящен ряд российских [1][2][3][4][5][6][7][8][9][10][11] и иностранных публикаций [12][13][14][15][16][17][18][19][20].…”