Integrated Methodology for Evaluation of Energy Performance of the Building Enclosures — Part 1: Test Program Development

Abstract

As a result of increased concern with energy consumption in the industrial world, it is only natural to look towards the building sector to seek significant improvements to meet expectations of the society. After all, the building sector consumes more energy than the transportation sector. Yet, the procedures that are used to define the thermal performance of, for example a wall, are typically based on the tests performed on dry materials, without consideration of air and moisture movements. In other words, these tests represent arbitrary rating conditions because we know that the energy performance of materials and building assemblies are affected by moisture and air flows. It is believed that to improve their energy performance one must have more precise means of evaluation of their field performance that would also include the consideration of air and moisture transfer conditions. In the first part of this article a background for the evaluation of thermal performance by traditional testing with calibrated boxes shows that use of these tests is limited. The average heat flow that they measure is sufficient to rate the wall assemblies but insufficient to calculate its thermal performance under field conditions. To include the effect of climate on thermal performance one must use computer models that are capable of simultaneous calculations of heat, air, and moisture transfer. Effectively, to characterize energy performance of the building enclosure one must simultaneously use assembly testing and modeling, i.e., an integrated methodology. In the second part of the article, this integrated testing and modeling methodology is applied to a few selected residential and commercial walls to highlight the magnitude of air flow effects on the steady-state thermal resistance. The integrated methodology proposed by Syracuse University includes several other aspects of hygrothermal performance evaluations. Those aspects will be addressed in later parts of this article series.

A concept of integrated environmental approach for building upgrades and new construction: Part 1—setting the stage

“…Energy+) allow inclusion of two- or three-dimensional model segments, one does not use this facility for inclusion of the HT modeling as a subset of energy modeling. Despite many research articles (Bomberg and Thorsell, 2008; Kosny et al, 2007; Lstiburek, 1999; Lstiburek et al, 2000, 2002; Said et al, 1997; Tamura, 1975; Tamura et al, 1974; Tamura and Wilson, 1963, 1966, 1967; Thorsell and Bomberg, 2008, 2011) highlighting effects of air and moisture on energy calculations with exception of some discussed in International Energy Agency (IEA) Annex 41, the whole-building energy models do not include effects of air and moisture transfer through walls.…”

A concept of capillary active, dynamic insulation integrated with heating, cooling and ventilation, air conditioning system

“…4.2 Scope of the research project As discussed elsewhere, hygrothermal models currently available in public domain are not suitable for real-time simultaneously occurring heat, air and moisture transfer in construction assemblies. The heat and moisture transfer calculations have been verified in endless cases, and providing that material characteristics are independently verified [5] can be used for integrated thermal modeling and testing work [22][23]. Yet, measurements and modeling of air flow effects on thermal performance and interaction between air and moisture present many unresolved problems.…”

Energy efficiency and thermal performance of lightweight steel-framed (LSF) construction: A review

“…However, since the energy performance of materials and building assemblies are significantly affected by moisture and air flows, the traditional testing using calibrated boxes may need to be improved [40]. Bomberg and Thorsell [52] proposed a new methodology (including both testing and modeling approaches) to evaluate the thermal performance of building enclosures under field conditions. The authors take into account the effect of thermal bridges, moisture and air flows, and they applied the methodology to evaluate the thermal performance of few residential walls [53] and steel-based commercial walls [54].…”