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Energy Efficient Retrofits
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New buildings account for a relatively small percentage of the energy used in the building sector. Retrofitting existing housing and commercial/industrial facilities is an important goal in terms of energy savings. It is also a complex endeavor, with many factors to consider, from preserving historic features to controlling costs.
The following articles and reports discuss a wide variety of materials, situations and techniques that may be encountered when undertaking an energy-efficient retrofit. As well, many case studies are provided to illustrate how to do retrofits right.
This digest reviews the moisture control principles that must be followed for a successful insulated retrofit of a solid load-bearing masonry wall. Two possible approaches to retrofitting such walls are presented and compared.
The American Foursquare, a Sears, Roebuck & Co. kit home, was a staple of small American towns between 1908 and 1940. More than 100,000 of them were built in America. Homes built prior to 1980 make up 80% of the housing stock in the United States, and are responsible for a majority of the residential energy use in the country. All of the renovations used systems engineering principles to ensure good indoor air quality and longterm durability while providing deep energy reductions. This posting is permission of ASHRAE. Additional reproduction, distribution, or transmission in either print or digital form is not permitted without ASHRAE's prior written permission.
What we learned from updating a 16-year-old deep-energy retrofit. Reprinted with permission from Fine Homebuilding, February/March 2012, pages 55-59.
Can a 150-year-old house approach zero energy use? Three case studies point the was from the 19th to the 21st century. Reprinted with permission from Fine Homebuilding, April/May 2008, pages 51-57.
This paper is from the proceedings of the Thermal Performance of the Exterior Envelopes of Whole Buildings XI International Conference, December 5-9, 2010 in Clearwater, Florida. The issues of climate change, energy security, and economics are all strong drivers for improving energy efficiency levels in a variety of sectors. In residential construction, although some inroads have been made in new houses, the stock of existing housing represents a huge opportunity for energy retrofits. The vanguard of these efforts has been pushing toward retrofitting very high insulation levels (i.e., “superinsulation,” or “deep energy retrofits”). Several cold-climate residential retrofit projects have been completed using an exterior insulation approach on light-frame above-grade walls. This type of retrofit is a reasonable step if a recladding of the building is already being done for aesthetic or ongoing maintenance reasons. The methods demonstrated here result in walls with insulation levels in the R-35 to R-40 range. This paper presents many of the lessons learned from these experiences, including overall enclosure strategies, such as air barriers, drainage planes, and moisture control. Several case-specific solutions to particular problems are described, including exterior air barrier approaches, wall sill replacement, and several approaches dealing with window penetrations. In addition, detailing recommendations and economic analysis of these measures are presented. Hygrothermal simulations were run to evaluate the changes in sensitivity to moisture intrusion due to these retrofit measures.
This paper is from the proceedings of the Thermal Performance of the Exterior Envelopes of Whole Buildings XI International Conference, December 5-9, 2010 in Clearwater, Florida. This paper summarizes some of the limitations of the various approaches to assessing the freeze-thaw resistance of brick masonry units and presents a detailed methodology for using frost dilatometry to determine the critical degree of saturation of brick material. Test results are presented for bricks from several historical load-bearing masonry. Recommendations are made for applying this approach together with hygrothermal model in the design of retrofit insulation projects.
Building Science Corporation seeks to further the energy efficiency market for cold climate, New England area retrofits by supporting projects based on solid building science fundamentals and verified implementation. The utility company National Grid engaged BSC as a partner to develop guidelines for its Deep Energy Retrofit Pilot Program. In addition to guideline development, BSC has acted as a consultant for these projects and others following similar retrofit strategies.
Basements can account for up to one quarter of the typical energy consumption in a house. Therefore, insulating foundations is a critical measure for achieving high performance buildings. This is important in both new construction and retrofits of existing buildings. The fundamental problems and “best practice solutions” for moisture-safe basement insulation have been well established. However, many foundations are damp (either due to bulk water or capillary “wicking” of moisture) or of a type of construction that is not easy or straightforward to insulate (such as rubble foundations). Damp foundation repair methods can be “leveraged” to provide energy efficiency benefits. An example of this “hybrid” approach is spray foam insulation, which can be an effective means of liquid phase water control (leaking basement), vapor phase water control (diffusion and air leakage transported condensation) as well as an effective insulation.
Through discussion of five case studies (test homes), this project evaluates strategies to elevate the performance of existing homes to a level commensurate with best-in-class implementation of high performance new construction homes. The test homes featured in this research activity participated in Deep Energy Retrofit (DER) Pilot Program sponsored by the electric and gas utility National Grid in Massachusetts and Rhode Island. Retrofit strategies are evaluated for impact on durability and indoor air quality in addition to energy performance.
This research project developed baseline engineering analysis to support the installation of thick layers of exterior insulation (2” to 8”) on existing masonry walls and wood framed walls through the use of wood furring strips (fastened through the insulation back to the structure) as a cladding attachment location. Furthermore, water management details necessary to connect the exterior insulated wall assemblies to roofs, balconies, decks, and windows were created to provide guidance on the integration of exterior insulation strategies with other enclosure elements.
This project examines implementation of advanced retrofit measures in the context of a large-scale weatherization program and the archetypal Chicago, Illinois, brick bungalow. In response to the apparent weatherization program limitations with respect to homes with masonry bearing wall construction, this research project examines two distinct strategies for insulating and air sealing the top of houses. One strategy applies best practice air sealing methods and a standard insulation method to the attic floor. The other strategy creates an unvented roof assembly using materials and methods typically available to weatherization contractors.
