Results for “exterior” | Engineering Papers

DOE OSTI2020

Evaluation of Exterior Shades at PNNL Lab Homes and Occupied Field Sites (Final Report)

In residential applications, heat transfer through windows accounts for a significant portion of a home’s cooling load. Exterior shades are window attachments that can be applied on the exterior-side of windows in a home. Exterior shades can reduce solar heat gain, reduce glare through a window, and improve comfort in the home. To assess the performance of residential exterior shades, the U.S. Department of Energy (DOE), Office of Energy Efficiency and Renewable Energy (EERE), Building Technologies Office (BTO) commissioned a series of field studies for exterior fabric shades to be performed by Pacific Northwest National Laboratory (PNNL) during the cooling seasons of 2019 and 2020. This report describes the experimental setup and results of these exterior shade field studies. PNNL, in collaboration with Lawrence Berkeley National Laboratory (LBNL), evaluated exterior shades at the PNNL Lab Homes and three occupied field sites in Richland, Washington. At the Lab Homes, the energy performance of exterior shades was evaluated in a controlled side-by-side environment. At the occupied field sites, exterior shades were characterized by measuring shade usage, documenting installation practices, and surveying customer perspectives.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

DOE OSTI2015

Potential energy savings with exterior shades in large office buildings and the impact of discomfort glare

Exterior shades are highly efficient for reducing solar load in commercial buildings. Their impact on net energy use depends on the annual energy balance of heating, cooling, fan and lighting energy. This paper discusses the overall energy use intensity of various external shading systems for a prototypical large office building split into the different types of energy use and for different orientations and window sizes. Lighting energy was calculated for a constant lighting power as well as for dimmed lighting fixtures (daylighting control). In Section 3, slat angles and solar cut-off angles were varied for fixed exterior slat shading systems. While the most light-blocking shades performed best for the case without daylighting controls, the optimum cut-off angle with daylighting controls was found to be 30 deg for the office building prototype used in Chicago and Houston. For large window-to-wall (WWR) ratios, window related annual energy use could be reduced by at least 70 % without daylighting control and by a minimum of 86 % with daylighting control in average over all orientations. The occurrence of discomfort glare was is considered in Section 4 of the paper, which looks at the performance of commercially available exterior shading systems when an interior shade is used in addition to the exterior shade during hours when occupants would experience discomfort glare. Glare control impacts overall energy use intensity significantly for exterior shades with high transmittance, especially when daylighting controls are used. In these cases, exterior shades are only beneficial for window-to-wall areas ≥ 45% in the hot Houston climate. For smaller windows and in a heating/cooling climate like Chicago, exterior shades can increase energy consumption

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

DOE OSTI2020

Highly Insulated Wall Systems with Exterior Insulation of Polyisocyanurate under Different Facer Materials: Material Characterization and Long-Term Hygrothermal Performance Assessment

The application of exterior insulation in both new construction and retrofits is a common practice to enhance the energy efficiency of buildings. In addition to increased thermal performance, the rigid insulation can serve to keep the sheathing board warm and serve as a water-resistive barrier to keep moisture-related problems due to condensation and wind-driven rain. Polyisocyanurate (PIR) rigid boards have a higher thermal resistance in comparison to other commonly used exterior insulation boards. However, because of its perceived lower permeance, its use as exterior insulation is not very common. In this study, the hygrothermal property of PIR boards with different facer types and thicknesses is characterized. The material data obtained through experimental test and extrapolation is used in a long term hygrothermal performance assessment of a wood frame wall with PIR boards as exterior insulation. Results show that PIR with no facer has the smallest accumulated moisture on the sheathing board in comparison to other insulation boards. Walls with a bigger thickness of exterior insulation perform better when no vapor barrier is used. The PIR exterior insulation supports the moisture control strategy well in colder climates in perfect wall scenarios, where there is no air leakage and moisture intrusion. In cases where there is trapped moisture, the sheathing board has a higher moisture content with PIR boards with both aluminum or fiberglass type facers. An innovative facer material development for PIR boards can help efforts targeting improved energy-efficient and durable wall systems.

36 MATERIALS SCIENCE↗

DOE OSTI2016

Construction Guidelines for High R-Value Walls without Exterior Rigid Insulation

High R-value wall assemblies (R-40 and above) are gaining popularity in the market due to programs such as the U.S. Department of Energy Zero Energy Ready Home program, Passive House, Net Zero Energy Home challenges in several states, and highly incentivized retrofit programs. In response to this demand, several builders have successfully used double-wall systems to achieve higher R-values in thicker, framed walls. To builders of conventional stick-framed homes, often one of the most appealing features of double-wall systems is that there are very few new exterior details. Exterior sheathings, structural bracings, house wraps or building paper, window and door flashings, and siding attachments are usually identical to good details in conventional framed-wall systems. However, although the details in double-wall systems are very similar to those in conventional stick framing, there is sometimes less room for error. Several studies have confirmed colder temperatures of exterior sheathing in high R-value wall assemblies that do not have exterior rigid foam insulation. These colder temperatures can lead to increased chances for condensation from air exfiltration, and they have the potential to result in moisture-related problems (Straube and Smegal 2009, Arena 2014, Ueno 2015). The information presented in this guide is intended to reduce the risk of failure in these types of assemblies, increase durability, and reduce material brought to landfills due to failures and resulting decay. Although this document focuses on double-wall framing techniques, the majority of the information about how to properly construct and finish high R-value assemblies is applicable to all wall assemblies that do not have foam insulation installed on the exterior of the structural sheathing. The techniques presented have been shown through field studies to reduce the likelihood of mold growth and moisture-related damage and are intended for builders, framing contractors, architects, and consultants involved in designing and building super-insulated homes. The information is applicable to both new construction and gut-rehabilitation projects in Climate Zones 5 and higher.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

DOE OSTI2013

Project Overcoat - An Exploration of Exterior Insulation Strategies for 1-1/2-Story Roof Applications in Cold Climates

The development of an alternative method to interior-applied insulation strategies or exterior applied 'band-aids' such as heat tapes and ice belts may help reduce energy needs of millions of 1-1/2 story homes while reducing the risk of ice dam formation. A potential strategy for energy improvement of the roof is borrowed from new construction best practices: Here an 'overcoat' of a continuous air, moisture, and thermal barrier is applied on the outside of the roof structure for improved overall performance. The continuous insulation of this approach facilitates a reduction in thermal bridging which could further reduce energy consumption and bring existing homes closer to meeting the Building America goals for energy reduction. Research favors an exterior approach to deep energy retrofits and ice dam prevention in existing homes. The greatest amount of research focuses on whole house deep energy retrofits leaving a void in roof-only applications. The research is also void of data supporting the hygrothermal performance, durability, constructability, and cost of roof-only exterior overcoat strategies. Yet, contractors interviewed for this report indicate an understanding that exterior approaches are most promising for mitigating ice dams and energy loss and are able to sell these strategies to homeowners.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

DOE OSTI2014

Spray Foam Exterior Insulation with Stand-Off Furring

IBACOS, in collaboration with GreenHomes America, was contracted by the New York State Energy Research and Development Authority to research exterior wall insulation solutions. This research investigated cost-effective deep energy retrofit (DER) solutions for improving the building shell exterior while achieving a cost-reduction goal, including reduced labor costs to reach a 50/50 split between material and labor. The strategies included exterior wall insulation plus energy upgrades as needed in the attic, mechanical and ventilation systems, and basement band joist, walls, and floors. The work can be integrated with other home improvements such as siding or window replacement. This strategy minimizes physical connections to existing wall studs, encapsulates existing siding materials (including lead paint) with spray foam, and creates a vented rain screen assembly to promote drying. GreenHomes America applied construction details created by IBACOS to a test home. 2x4 framing members were attached to the wall at band joists and top plates using 'L' clips, with spray foam insulating the wall after framing was installed. Windows were installed simultaneously with the framing, including extension jambs. The use of clips in specific areas provided the best strength potential, and 'picture framing' the spray foam held the 2x4s in place. Short-term testing was performed at this house, with monitoring equipment installed for long-term testing. Testing measurements will be provided in a later report, as well as utility impact (before and after), costs (labor and materials), construction time, standard specifications, and analysis for the exterior wall insulation strategy.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

DOE OSTI2014

Initial and Long-Term Movement of Cladding Installed Over Exterior Rigid Insulation

Changes in the International Energy Conservation Code (IECC) from 2009 to 2012 have resulted in the use of exterior rigid insulation becoming part of the prescriptive code requirements. With more jurisdictions adopting the 2012 IECC builders are going to finding themselves required to incorporate exterior insulation in the construction of their exterior wall assemblies. For thick layers of exterior insulation (levels greater than 1.5 inches), the use wood furring strips attached through the insulation back to the structure has been used by many contractors and designers as a means to provide a convenient cladding attachment location. However, there has been a significant resistance to its widespread implementation due to a lack of research and understanding of the mechanisms involved and potential creep effects of the assembly under the sustained dead load of a cladding. This research was an extension on previous research conducted by BSC in 2011, and 2012. Each year the understanding of the system discrete load component interactions, as well as impacts of environmental loading has increased. The focus of the research was to examine more closely the impacts of screw fastener bending on the total system capacity, effects of thermal expansion and contraction of materials on the compressive forces in the assembly, as well as to analyze a full years worth of cladding movement data from assemblies constructed in an exposed outdoor environment.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

DOE OSTI2014

Initial and Long-Term Movement of Cladding Installed Over Exterior Rigid Insulation

Changes in the International Energy Conservation Code (IECC) from 2009 to 2012 have resulted in the use of exterior rigid insulation becoming part of the prescriptive code requirements. With more jurisdictions adopting the 2012 IECC builders will be required to incorporate exterior insulation in the construction of their exterior wall assemblies. For thick layers of exterior insulation (levels greater than 1.5 inches), the use of wood furring strips attached through the insulation back to the structure has been used by many contractors and designers as a means to provide a convenient cladding attachment location. This research was an extension on previous research conducted by Building Science Corporation in 2011, and 2012. Each year the understanding of the system discrete load component interactions, as well as impacts of environmental loading, has increased. The focus of the research was to examine more closely the impacts of screw fastener bending on the total system capacity, effects of thermal expansion and contraction of materials on the compressive forces in the assembly, as well as to analyze a full year’s worth of cladding movement data from assemblies constructed in an exposed outdoor environment.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

DOE OSTI2014

Spray Foam Exterior Insulation with Stand-Off Furring

IBACOS, in collaboration with GreenHomes America, was contracted by the New York State Energy Research and Development Authority to research exterior wall insulation solutions. This research investigated cost-effective deep energy retrofit (DER) solutions for improving the building shell exterior while achieving a cost-reduction goal, including reduced labor costs to reach a 50/50 split between material and labor. The strategies included exterior wall insulation plus energy upgrades as needed in the attic, mechanical and ventilation systems, and basement band joist, walls, and floors. The work can be integrated with other home improvements such as siding or window replacement. This strategy minimizes physical connections to existing wall studs, encapsulates existing siding materials (including lead paint) with spray foam, and creates a vented rain screen assembly to promote drying. GreenHomes America applied construction details created by IBACOS to a test home. 2x4 framing members were attached to the wall at band joists and top plates using "L" clips, with spray foam insulating the wall after framing was installed. Windows were installed simultaneously with the framing, including extension jambs. The use of clips in specific areas provided the best strength potential, and "picture framing" the spray foam held the 2x4s in place. Short-term testing was performed at this house, with monitoring equipment installed for long-term testing. Testing measurements will be provided in a later report, as well as utility impact (before and after), costs (labor and materials), construction time, standard specifications, and analysis for the exterior wall insulation strategy.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

DOE OSTI2014

Building America Case Study: Initial and Long-Term Movement of Cladding Installed Over Exterior Rigid Insulation (Fact Sheet)

Changes in the International Energy Conservation Code (IECC) from 2009 to 2012 have resulted in the use of exterior rigid insulation becoming part of the prescriptive code requirements. With more jurisdictions adopting the 2012 IECC builders are going to finding themselves required to incorporate exterior insulation in the construction of their exterior wall assemblies. For thick layers of exterior insulation (levels greater than 1.5 inches), the use wood furring strips attached through the insulation back to the structure has been used by many contractors and designers as a means to provide a convenient cladding attachment location. However, there has been a significant resistance to its widespread implementation due to a lack of research and understanding of the mechanisms involved and potential creep effects of the assembly under the sustained dead load of a cladding. This research was an extension on previous research conducted by BSC in 2011, and 2012. Each year the understanding of the system discrete load component interactions, as well as impacts of environmental loading has increased. The focus of the research was to examine more closely the impacts of screw fastener bending on the total system capacity, effects of thermal expansion and contraction of materials on the compressive forces in the assembly, as well as to analyze a full years worth of cladding movement data from assemblies constructed in an exposed outdoor environment.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

DOE OSTI2014

Technology Solutions Case Study: Initial and Long-Term MOvement of Cladding Installed Over Exterior Rigid Insulation

Changes in the International Energy Conservation Code (IECC) from 2009 to 2012 have resulted in the use of exterior rigid insulation becoming part of the prescriptive code requirements. With more jurisdictions adopting the 2012 IECC, builders will be required to incorporate exterior insulation in the construction of their exterior wall assemblies. For thick layers of exterior insulation (levels greater than 1.5 inches), the use of wood of furring strips attached through the insulation back to the structure has been used by many contractors and designers as a means to provide a convenient cladding attachment location. However, there has been resistance to its widespread implementation due to a lack of research and understanding of the mechanisms involved and potential creep effects of the assembly under the sustained dead load of a cladding. This research conducted by Building Science Corporation evaluated the system mechanics and long-term performance of this technique.

BSC↗

DOE OSTI2013

Evaluation of Two CEDA Weatherization Pilot Implementations of an Exterior Insulation and Over-Clad Retrofit Strategy for Residential Masonry Buildings in Chicago

This project examines the implementation of an exterior insulation and over-clad strategy for brick masonry buildings in Chicago. The strategy was implemented at a free-standing two story two-family dwelling and a larger free-standing multifamily building. The test homes selected for this research represent predominant housing types for the Chicago area. High heating energy use typical in these buildings threaten housing affordability. Uninsulated mass masonry wall assemblies also have a strongly detrimental impact on comfort. Significant changes to the performance of masonry wall assemblies is generally beyond the reach of typical weatherization (Wx) program resources. The Community and Economic Development Association of Cook County, Inc. (CEDA) has secured a Sustainable Energy Resources for Consumers (SERC) innovation grant sponsored by the United States Department of Energy (DOE). This grant provides CEDA the opportunity to pursue a pilot implementation of innovative approaches to retrofit in masonry wall enclosures. The exterior insulation and over-clad strategy implemented through this project was designed to allow implementation by contractors active in CEDA weatherization programs and using materials and methods familiar to these contractors. The retrofit measures are evaluated in terms of feasibility, cost and performance. Through observations of the strategies implemented, the research described in this report identifies measures critical to performance as well as conditions for wider adoption. The research also identifies common factors that must be considered in determining whether the exterior insulation and over-clad strategy is appropriate for the building.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

DOE OSTI2013

Excavationless Exterior Foundation Insulation Exploratory Study

Building science research supports installing exterior (soil side) foundation insulation as the optimal method to enhance the hygrothermal performance of new homes. With exterior foundation insulation, water management strategies are maximized while insulating the basement space and ensuring a more even temperature at the foundation wall. Controlling for bulk water, vapor, and wall temperature differential reduces the risk of rot and mold formation to insulation and building materials, thereby improving opportunities for structural integrity, indoor air quality, comfort, and energy efficiency. The intent of this study by the NorthernSTAR Building America Partnership team is to search for combinations of existing technologies that could enable a minimally invasive, cost-competitive, easily deployable method of upgrading soil-side foundation insulation in existing buildings. Currently, insulating foundation walls on the exterior side involves exposing the foundation wall using an excavator. Following excavation, these walls can be waterproofed, and are typically insulated with board foam in a process similar to new construction. This process is expensive and highly disruptive to the landscape and the homeowner. Also, barriers such as porches and sidewalks prevent trenching. An ideal approach would involve excavating a very narrow trench directly next to the foundation wall. Full-height foundation wall insulation might be desired, so the trenching technology should be able to dig to a depth of 7 or 8 ft. Because houses often have hardscape obstructions that are expensive to demolish and remove, the ideal technology would be capable of digging under at least some obstructions that would remain in place.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

DOE OSTI2013

Cladding Attachment Over Thick Exterior Insulating Sheathing (Fact Sheet)

The addition of insulation to the exterior of buildings is an effective means of increasing the thermal resistance of wood-framed walls and mass masonry wall assemblies. The location of the insulation on the exterior of the structure has many direct benefits, including better effective R-value from reduced thermal bridging, better condensation resistance, reduced thermal stress on the structure, as well as other commonly associated improvements such as increased airtightness and improved water management. For thick layers of exterior insulation (more than 1.5 in.), the use of wood furring strips attached through the insulation back to the structure has been used by many contractors and designers as a means to provide a convenient cladding attachment location. Although the approach has proven effective, there is significant resistance to its widespread implementation due to a lack of research and understanding of the mechanisms involved in the development of the vertical displacement resistance capacity. In addition, the long-term in-service performance of the system has been questioned due to potential creep effects of the assembly under the sustained dead load of the cladding and effects of varying environmental conditions. In addition, the current International Building Code (IBC) and International Residential Code (IRC) do not have a provision that specifically allows this assembly.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

DOE OSTI2014

Evaluating an Exterior Insulation and Finish System for Deep Energy Retrofits

Exterior insulation and finish systems (EIFS) are proprietary synthetic formulations that are applied to the exterior walls of buildings to serve as insulation and exterior cladding. The insulation thickness can vary from less than one inch to a foot or more. In this project the applicability of EIFS for residential deep energy retrofits was investigated through modeling and a case study home. The home was retrofitted using a site-applied four-inch-thick EIFS. Site-specific details were developed as required for the residential retrofit application. Site work and the costs of the EIFS system were documented. The demonstration home was modeled using Building Energy Optimization energy and cost analysis software to explore cost effectiveness of various EIFS insulation thicknesses in two climate locations.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

DOE OSTI2015

Exterior Insulation Implications for Heating and Cooling Systems in Cold Climates

The New York State Energy Research and Development Authority (NYSERDA) is interested in finding cost-effective solutions for deep energy retrofits (DERs) related to exterior wall insulation in a cold climate, with targets of 50% peak load reduction and 50% space conditioning energy savings. The U.S. Department of Energy Building America team, IBACOS, in collaboration with GreenHomes America, Inc. (GHA), was contracted by NYSERDA to research exterior wall insulation solutions. In addition to exterior wall insulation, the strategies included energy upgrades where needed in the attic, mechanical and ventilation systems, basement, band joist, walls, and floors. Under Building America, IBACOS is studying the impact of a “thermal enclosure” DER on the sizing of the space conditioning system and the occupant comfort if the thermal capacity of the heating and cooling system is dramatically downsized without any change in the existing heating and cooling distribution system (e.g., size, tightness and supply outlet configurations).

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

DOE OSTI2015

Exterior Insulation Implications for Heating and Cooling Systems in Cold Climates

The New York State Energy Research and Development Authority (NYSERDA) is interested in finding cost-effective solutions for deep energy retrofits (DERs) related to exterior wall insulation in a cold climate, with targets of 50% peak load reduction and 50% space conditioning energy savings. The U.S. Department of Energy Building America team, IBACOS, in collaboration with GreenHomes America, Inc. (GHA), was contracted by NYSERDA to research exterior wall insulation solutions. In addition to exterior wall insulation, the strategies included energy upgrades where needed in the attic, mechanical and ventilation systems, basement, band joist, walls, and floors. Under Building America, IBACOS is studying the impact of a “thermal enclosure” DER on the sizing of the space conditioning system and the occupant comfort if the thermal capacity of the heating and cooling system is dramatically downsized without any change in the existing heating and cooling distribution system (e.g., size, tightness and supply outlet configurations).

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

DOE OSTI2014

Evaluating an Exterior Insulation and Finish System for Deep Energy Retrofits

Exterior insulation and finish systems (EIFS) are proprietary synthetic formulations that are applied to the exterior walls of buildings to serve as insulation and exterior cladding. The insulation thickness can vary from less than one inch to a foot or more. In this project the applicability of EIFS for residential deep energy retrofits was investigated through modeling and a case study home. The home was retrofitted using a site-applied four-inch-thick EIFS. Site-specific details were developed as required for the residential retrofit application. Site work and the costs of the EIFS system were documented. The demonstration home was modeled using Building Energy Optimization energy and cost analysis software to explore cost effectiveness of various EIFS insulation thicknesses in two climate locations.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗