A technique for improving the thermal performance of lightweight steel- and wood-framed building assemblies is introduced in this paper. In this approach, rigid extruded insulation material is applied only to the framing members themselves (studs, plates, doubles, headers, etc.), effectively creating a composite member composed of insulation and structural framing. The depth of the envelope cavity is thereby extended by an amount that is equal to the thickness of the rigid insulation employed.
Modem, massive building envelope technologies (masonry and concrete systems) are gaining acceptance by builders today. All U.S. thermal building standards, including ASHRAE 90.1and90.2 and the Model Energy Code, are linked to the steady-state clear wall R-value. They also have separate requirements for high mass walls. Very often, only steady-state R-value is used as a measure of the steady-state thermal performance of the wall. This value does not reflect the dynamic thermal performance of massive building envelope systems.
An insulated wall can be supported internally by thin steel studs. There will be extra heat loss caused by the metal U-studs, but slitting the web of the U-studs perpendicular to the heat flow direction reduces this heat loss. Calculation of the heat transmittance is a difficult numerical problem due to the high ratio of thermal conductivity between the insulation and the steel. This study presents result of calculations in three dimensions. The proper choice of the numerical mesh is discussed. Simplified equations for the U-factor are derived and implemented ill a computer program.
The purpose of this project was to devise a simple, experimentally validated method for quantifying the energy impacts of exterior envelope air leakage. Four full-size exterior envelope test specimens, two opaque wall systems and two fenestration systems, were built for determining simultaneous conductive and convective heat loss. The two opaque clear wall sections were metal-faced sandwich panel and cold formed steel frame.
This paper presents a numerical model to investigate the foundation heat transfer from conditioned basements when the ground is composed of multilayered strata with different thermal properties. The model is used to determine the thermal performance of several basement insulation configurations under both steady-state and transient conditions. It is found that the nonhomogeneity of the soil significantly affects the heat transfer from uninsulated basement walls rather than the basement floor or insulated basement walls.
This paper outlines the methods and results of a four-year project that measured heat flows through two uninsulated slab-on ground floors on nominally wet soils. One floor was on peat soil, the other on clay, and water table depths were 0.5 m to 1.0 m through most of the year. Heat fluxes were measured over the whole floor using heat flux transducers (HFT) at the concrete floor surface, and temperatures were measured by thermocouple, continuously for four years. The soil conductivities and soil temperatures were measured daily at 11 positions near one edge of the floors.
The low-slope roofs of ten cold storage buildings in the Dallas area were examined visually and thermo graphically (Tobiasson and Korhonen 1985) from above and below. Two inch (51 mm) diameter cores were taken to verify infrared findings and to determine moisture contents for estimating wet thermal resistances (Tobiasson et al. 1991 ). Twelve inch (0.3 m) square specimens of many of the insulations were removed for laboratory studies of their thermal properties and structure.
This is a case study describing the procedures for locating, prioritizing, and repairing the causes of ice dam formation at a complex of over one hundred Northeast ski-area condominiums. The testing, performed on four typical units, was commissioned by the Owners Association to prove the feasibility of preventing ice dam formation without replacing all of the existing roofs and to determine the costs of this approach. Ice dam formation is one of the predominate problems for buildings in cold climates.