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The Consortium for Advanced Residential Buildings (CARB) conducted research to gain more insight into passive vents. Because passive vents are meant to operate in a general environment of negative apartment pressure, the research assessed whether these negative pressures prevail through a variety of environmental conditions.
Solar water heating systems are not new, but they have not become prevalent in most of the U.S. Most of the country is cold enough that indirect solar thermal systems are required for freeze protection, and average installed cost of these systems is $9,000 to $10,000 for typical systems on single-family homes. These costs can vary significantly in different markets and with different contractors, and federal and regional incentives can reduce these up-front costs by 50% or more. In western Massachusetts, an affordable housing developer built a community of 20 homes with a goal of approaching zero net energy consumption. In addition to excellent thermal envelopes and PV systems, the developer installed a solar domestic water heating system (SDHW) on each home. The Consortium for Advanced Residential Buildings (CARB), a research consortium funded by the U.S. Department of Energy Building America program, commissioned some of the systems, and CARB was able to monitor detailed performance of one system for 28 months.
To better understand and characterize heating performance, the U.S. Department of Energy Building America team, Consortium for Advanced Residential Buildings (CARB), monitored seven inverter-driven ASHPs across the northeast United States during the winter of 2013–2014.
Solar water heating systems are not new, but they have not become prevalent in most of the U.S. Most of the country is cold enough that indirect solar thermal systems are required for freeze protection, and average installed cost of these systems is $9,000 to $10,000 for typical systems on single-family homes. These costs can vary significantly in different markets and with different contractors, and federal and regional incentives can reduce these up-front costs by 50% or more. In western Massachusetts, an affordable housing developer built a community of 20 homes with a goal of approaching zero net energy consumption. In addition to excellent thermal envelopes and PV systems, the developer installed a solar domestic water heating system (SDHW) on each home. The Consortium for Advanced Residential Buildings (CARB), a research consortium funded by the U.S. Department of Energy Building America program, commissioned some of the systems, and CARB was able to monitor detailed performance of one system for 28 months.
In an effort to improve indoor air quality in high-performance, new construction, multifamily buildings, dedicated sources of outdoor air are being implemented. Passive vents are being selected by some design teams over other strategies because of their lower first costs and operating costs. The U.S. Department of Energy’s Building America research team Consortium for Advanced Residential Buildings constructed eight steps, which outline the design and commissioning required for these passive vents to perform as intended.
Traditionally, air-source heat pumps (ASHPs) have been used more often in warmer climates; however, some new ASHPs are gaining ground in colder areas. These systems operate at subzero (Fahrenheit) temperatures and many do not include backup electric resistance elements. There are still uncertainties, however, about capacity and efficiency in cold weather. Also, questions such as “how cold is too cold?” do not have clear answers. These uncertainties could lead to skepticism among homeowners; poor energy savings estimates; suboptimal system selection by heating, ventilating, and air-conditioning contractors; and inconsistent energy modeling. In an effort to better understand and characterize the heating performance of these units in cold climates, the U.S. Department of Energy Building America team, Consortium for Advanced Residential Buildings (CARB), monitored seven inverter-driven, ductless ASHPs across the Northeast. Operating data were collected for three Mitsubishi FE18 units, three Mitsubishi FE12 units, and one Fujitsu 15RLS2 unit. The intent of this research was to assess heat output, electricity consumption, and coefficients of performance (COPs) at various temperatures and load conditions. This assessment was accomplished with long- and short-term tests that measured power consumption; supply, return, and outdoor air temperatures; and airflow through the indoor fan coil.
Air sealing of building enclosures is a difficult and time-consuming process. Current methods in new construction require laborers to physically locate small and sometimes large holes in multiple assemblies and then manually seal each of them. This research study by Building America team Consortium for Advanced Residential Buildings demonstrated the automated air sealing and compartmentalization of buildings through the use of an aerosolized sealant developed by the Western Cooling Efficiency Center at University of California Davis. CARB demonstrated this new technology application in a multifamily building in Queens, NY. The effectiveness of the sealing process was evaluated by three methods: air leakage testing of overall apartment before and after sealing, point-source testing of individual leaks, and pressure measurements in the walls of the target apartment during sealing. Aerosolized sealing was successful by several measures in this study. Many individual leaks that are labor-intensive to address separately were well sealed by the aerosol particles. In addition, many diffuse leaks that are difficult to identify and treat were also sealed. The aerosol-based sealing process resulted in an average reduction of 71% in air leakage across three apartments and an average apartment airtightness of 0.08 CFM50/SF of enclosure area.
The Building America team Consortium for Advanced Residential Buildings (CARB) investigated a hybrid ventilation method that included the exhaust air from the crawl space as part of an ASHRAE 62.2-compliant whole-house ventilation strategy. The CARB team evaluated this hybrid ventilation method through long-term field monitoring of temperature, humidity, and pressure conditions within the crawl spaces of two homes (one occupied and one unoccupied) in New York state.
Solar domestic hot water (SDHW) systems have been installed on buildings for decades, but because of relatively high costs they have not achieved significant market penetration in most of the country. As more buildings move towards zero net energy consumption, however, many designers and developers are looking more closely at SDHW. In multifamily buildings especially, SDHW may be more practical for several reasons: (1) When designing for zero net energy consumption, solar water heating may be part of the lowest cost approach to meet water heating loads. (2.) Because of better scale, SDHW systems in multifamily buildings cost significantly less per dwelling than in single-family homes. (3) Many low-load buildings are moving away from fossil fuels entirely. SDHW savings are substantially greater when displacing electric resistance water heating. (4) In addition to federal tax incentives, some states have substantial financial incentives that dramatically reduce the costs (or increase the benefits) of SDHW systems in multifamily buildings. With support form the U.S. DOE Building America program, the Consortium for Advanced Residential Buildings (CARB) worked with a developer in western Massachusetts to evaluate a SDHW system on a 12-unit apartment building. Olive Street Development completed construction in spring of 2014, and CARB has been monitoring performance of the water heating systems since May 2014.
Heating, ventilating, and air-conditioning (HVAC) equipment must be right-sized to ensure energy performance and comfort. With limited low-load options in the HVAC market, many new-construction housing units are being fitted with oversized equipment that creates system efficiency, comfort, and cost penalties. To bridge the gap between currently available HVAC equipment that is oversized or inefficient and the rising demand for low-load HVAC equipment in the marketplace, HVAC equipment manufacturers need to be fully aware of the needs of the multifamily building and attached single-family (duplex and townhouse) home market. Over the past decade, Steven Winter Associates, Inc. (SWA) has provided certification and consulting services for hundreds of housing projects and has accrued a large pool of data that describe multifamily and attached single-family home characteristics. The U.S. Department of Energy’s Building America research team Consortium for Advanced Residential Buildings (CARB) compiled and analyzed these data to outline the characteristics of low-load dwellings such as the heating and cooling design loads.
Solar domestic hot water (SDHW) systems have been installed on buildings for decades, but because of relatively high costs they have not achieved significant market penetration in most of the country. As more buildings move towards zero net energy consumption, however, many designers and developers are looking more closely at SDHW. In multifamily buildings especially, SDHW may be more practical for several reasons: (1) When designing for zero net energy consumption, solar water heating may be part of the lowest cost approach to meet water heating loads. (2) Because of better scale, SDHW systems in multifamily buildings cost significantly less per dwelling than in single-family homes. (3) Many low-load buildings are moving away from fossil fuels entirely. SDHW savings are substantially greater when displacing electric resistance water heating. (4) In addition to federal tax incentives, some states have substantial financial incentives that dramatically reduce the costs (or increase the benefits) of SDHW systems in multifamily buildings. With support from the U.S. DOE Building America program, the Consortium for Advanced Residential Buildings (CARB) worked with a developer in western Massachusetts to evaluate a SDHW system on a 12-unit apartment building. Olive Street Development completed construction in spring of 2014, and CARB has been monitoring performance of the water heating systems since May 2014.
Solar domestic hot water (SDHW) systems have been installed on buildings for decades, but because of relatively high costs they have not achieved significant market penetration in most of the country. As more buildings move towards zero net energy consumption, however, many designers and developers are looking more closely at SDHW. In multifamily buildings especially, SDHW may be more practical for several reasons: 1) When designing for zero net energy consumption, solar water heating may be part of the lowest cost approach to meet water heating loads; 2) Because of better scale, SDHW systems in multifamily buildings cost significantly less per dwelling than in single-family homes; 3) Many low-load buildings are moving away from fossil fuels entirely. SDHW savings are substantially greater when displacing electric resistance water heating; and 4) In addition to federal tax incentives, some states have substantial financial incentives that dramatically reduce the costs (or increase the benefits) of SDHW systems in multifamily buildings. With support from the U.S. DOE Building America program, the Consortium for Advanced Residential Buildings (CARB) worked with a developer in western Massachusetts to evaluate a SDHW system on a 12-unit apartment building. Olive Street Development completed construction in spring of 2014, and CARB has been monitoring performance of the water heating systems since May 2014.
The U.S. Department of Energy’s Building America research team Consortium for Advanced Residential Buildings (CARB) worked with the EcoVillage cohousing community in Ithaca, New York, on the Third Residential EcoVillage Experience neighborhood. This communityscale project consists of 40 housing units—15 apartments and 25 single-family residences. Units range in size from 450 ft2 to 1,664 ft2 and cost from $80,000 for a studio apartment to $235,000 for a three- or four-bedroom single-family home. For the research component of this project, CARB analyzed current heating system sizing methods for superinsulated homes in cold climates to determine if changes in building load calculation methodology should be recommended. Actual heating energy use was monitored and compared to results from the Air Conditioning Contractors of America’s Manual J8 (MJ8) and the Passive House Planning Package software. Results from that research indicate that MJ8 significantly oversizes heating systems for superinsulated homes and that thermal inertia and internal gains should be considered for more accurate load calculations.
With funding from the Building America Program, part of the U.S. Department of Energy Building Technologies Office, the Consortium for Advanced Residential Buildings (CARB) worked with BrightBuilt Home (BBH) to evaluate and optimize building systems. CARB’s work focused on a home built by Black Bros. Builders in Lincolnville, Maine (International Energy Conservation Code Climate Zone 6). As with most BBH projects to date, modular boxes were built by Keiser Homes in Oxford, Maine.
With support from the U.S. Department of Energy Building America Program, the Consortium for Advanced Residential Buildings (CARB) worked with a developer in western Massachusetts to evaluate a SDHW system on a 12-unit apartment building. Olive Street Development completed construction in the spring of 2014, and CARB has been monitoring the performance of the water-heating systems since May 2014.
The U.S. Department of Energy Building America research team Consortium for Advanced Residential Buildings (CARB) partnered with Preferred Builders, a previous CARB partner and builder of the Performance House (DOE 2013) and the owners of a 1960s split-level home in Westport, Connecticut, to evaluate and implement a cost-effective solution package that met the requirements of 30% source energy savings compared to the pre-retrofit performance. This home had already been updated aesthetically (kitchen and bathrooms), so the owners wanted the energy-efficiency measures to be as non-disruptive to the interior finishes as possible.
Moisture problems within the building shell can be caused by a number of factors including excess interior moisture that is transported into the wall through air leakage and vapor drive, bulk water intrusion from leaks and wind-driven rain, capillary action from concrete to wood connections, and through wetted building materials such as siding wetted from rain splash back. With the increasing thickness of walls, moisture issues could increase. Several builders have successfully used “double-wall” systems to more practically achieve higher R-values in thicker framed walls. A double wall typically consists of a load-bearing external frame wall constructed with 2 × 4 framing at 16 in. on center using conventional methods. After the building is enclosed, an additional frame wall is constructed several inches inside the load-bearing wall. Several researchers have used moisture modeling software to conduct extensive analysis of these assemblies; however, little field research has been conducted to validate the results. In this project, the Building America research team Consortium for Advanced Residential Buildings monitored a double-stud assembly in climate zone 5A to determine the accu¬racy of moisture modeling and make recommendations to ensure durable and efficient assemblies.
Low-load options in the heating, ventilating, and air-conditioning (HVAC) market are limited, so many new-construction housing units are being fitted with oversized equipment that results in penalties in system efficiency, comfort, and cost. To bridge the gap between currently available HVAC equipment and the rising demand for low-load HVAC equipment in the marketplace, HVAC equipment manufacturers need to be fully aware of the needs of the multifamily building and attached single-family home markets. Over the past decade, Steven Winter Associates, Inc. has provided certification and consulting services for hundreds of housing projects and has accrued a large pool of data that describe multifamily and attached single-family home characteristics. In this project, the research team Consortium for Advanced Residential Buildings (CARB) compiled and analyzed the data from 941 low-load buildings in the Northeast and Mid-Atlantic regions to outline the heating and cooling design load characteristics of low-load dwellings. Within this data set, CARB found that only 1% of the dwellings had right-sized (within 25% of design load) heating equipment and 6% had right-sized cooling equipment.