As energy code requirements for the thermal performance of buildings increase over time, the requirements of roofing systems are becoming more stringent. One of the requirements focuses on the minimum amount of insulation within a roofing system when it is installed in a continuous manner, entirely above the deck. However, the energy code does not clearly address the reduction of the roof system's thermal performance due to penetrations that create thermal bridges through the system. These penetrations can come in the form of fasteners used in a mechanically attached roof system or from much larger penetrations used to support rooftop equipment and accessories. It is common for roofs to contain several different types and combinations of penetrations such as roof drains, vent pipes, mechanical ducts, duct supports, mechanical equipment, roof screens, parapet bracing, ships ladders, and photovoltaic panels. Two- and three-dimensional thermal modeling will be utilized to study and quantify the impact of the thermal bridging of typical penetrations through a roof system. Results from previous studies related to the thermal impact of mechanically fastened roofs will be reviewed to gain additional insight related to this issue. A low-slope roof with a single-ply roof cover and industry standard roof details will be utilized as the basis for this evaluation. This paper will compare a variety of penetrations to a roof without any penetrations to evaluate the impact on the overall thermal performance of a roofing system. In addition, various thicknesses of insulation will be evaluated in this study.

In masonry veneer wall assemblies, lateral ties are a structural requirement. Traditionally they are fabricated from steel, which has a high conductivity. Building codes require that ties be tightly spaced and, in most climate zones, it requires continuous insulation in the majority of wall assemblies. Continuous insulation in the cavity space results in the ties penetrating the insulation layer. The combination of material, required spacing, and location of insulation result in most masonry veneer walls being constructed with a significant amount of thermal bridges causing a loss in thermal performance. At present, the building industry typically does not account for these thermal bridges and their effect on the exterior enclosure. We speculate that the reasoning for this is primarily due to a lack of industry accepted information relative to the thermal reduction of the masonry wall system from the inclusion of ties. The purpose of this paper is to begin providing this missing information. Using three dimensional Finite Element Modeling software (thermal modeling), common masonry wall assemblies are studied by simulating them with and without masonry ties. This comparative analysis quantifies the impact of masonry ties on the thermal performance of each wall assembly studied. In recent history, large steps, such as continuous insulation requirements, thermally broken fenestration systems, low-e coatings, and air barrier technologies have been introduced to increase the performance of exterior enclosures and thus the overall efficiency of the built environment. The industry now must focus its attention on the details of wall systems to take the next steps in incrementally increasing building efficiency. Data obtained through three dimensional thermal modelling is used to address the impact masonry ties have on the thermal performance of wall systems. Finally, alternate materials are evaluated and considered as a means to improve thermal performance of the masonry veneer wall assemblies.

Current methods of evaluating the risk of condensation on fenestration systems generally include two-dimensional computer modeling and sometimes laboratory testing. This is not sufficient for curtain wall systems that incorporate areas of insulated spandrel. In most curtain walls, mullions can extend from a warmer interior environment into a colder insulated spandrel. The mullions function as thermal bridges and may increase the potential for condensation on or within the system. The impact will vary depending on several factors such as the type of vision and spandrel glazing, insulating glass unit (IGU) spacer type, insulation thickness, location of the insulation, and vapor barrier methodology. Industry standard evaluation methods do not address this heat transfer. Two-dimensional computer modeling can be used to assess transitions between vision and spandrel areas. Because it is only a two-dimensional evaluation, it cannot determine the heat flow in the third dimension. Laboratory testing such as the American Architectural Manufacturers Association’s AAMA 1503, Voluntary Test Method for Thermal Transmittance and Condensation Resistance of Windows, Doors, and Glazed Wall Sections, is sometimes used to provide measured results of condensation resistance. Manufacturers typically do not include spandrel conditions when testing the performance of a system. The purpose of this paper is to evaluate the relative impact of three-dimensional heat flow through curtain wall vision/spandrel conditions related to the potential for condensation to determine if there is an increased risk of condensation at the vision/spandrel interface and to demonstrate that the use of three-dimensional thermal modeling can be readily repeated for multiple project specific variables without the cost of laboratory testing.