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Case study of a DOE 2021 Housing Innovation Award winning custom home in a cold climate that got a HERS 5 with PV, with 3,934 square feet, ENERGY STAR appliances and windows, LED lighting, and a heat pump water heater.
Case study of a DOE 2020 Housing Innovation Award winning custom home in a cold climate that got a HERS 29 with PV, with 1,793 square feet, high insulation levels in the attic, walls, and under the slab, plus ENERGY STAR appliances, and solar PV panels.
Manufactured homes offer American consumers an affordable option for decent single-family detached housing. For working-class American families in many U.S. markets, manufactured homes are the first step toward home ownership. They now make up 10% of all new homes constructed in the United States, with higher percentages in the south and in rural communities. To help encourage the production of homes that are more durable, healthy, efficient, and disaster resistant, the U.S. Department of Energy is bringing its building science research to the manufactured housing industry through DOE’s Zero Energy Ready Manufactured Home (ZER-MH) program, which provides technical assistance and voluntary guidelines to manufactured home builders. Homes built to these guidelines are better able to handle power outages and less likely to experience moisture issues, offering a better product option for American families. This higher quality is evidenced by energy modeling which shows homes manufactured to these voluntary guidelines will typically use half the energy of manufactured homes built to the current minimum requirements of the U.S. Department of Housing and Urban Development (HUD)’s Manufactured Housing and Construction Safety Standard (MHCSS). These homes can also reduce critical energy demand during the busiest hours of the day, typically late afternoon and early evening in the summer when air conditioning demand is highest and mornings in the winter when furnaces and heaters are heating up. Reducing electricity demand during these peak periods when electricity rates are at their highest reduces costs for American families while freeing up capacity on overburdened energy distribution networks. Builders participating in the DOE ZER-MH program are eligible for a tax incentive via the 45L tax credit, which helps to offset the costs of ZER-MH upgrades, enabling builders to offer these certified homes at no additional cost. Together these factors enable manufactured homes to offer home buyers a housing option that is both affordable to finance and affordable to operate, with lower monthly mortgage payments and lower monthly energy bills.
In this conference paper for the ASHRAE Buildings XV conference, December 2022, PNNL staff share key metrics for companies who are combining off site construction with certification to the U.S. Department of Energy’s Zero Energy Ready Home program to create homes that are both cost effective to construct and high performance to live in. Key performance metrics and measures for modular, panelized, and SIP homes are compared against all homes in the DOE Zero Energy Ready Home program and against new homes built to code. These metrics show that off-site construction homes got similar or better energy performance to site-built homes, and in the case of modular and panelized, at considerably lower average cost than site-built homes. The paper also highlights the experiences of two DOE Zero Energy Ready Home builders who employ offsite construction methods. One builder constructs production homes using pre-assembled panels. The other builder designs and ships kit homes all over the United States. The paper will focus on the optimum value engineering aspects of the panelized construction processes used by each builder to identify management and production practices employed by the builders to operate profitably while meeting high energy performance goals, despite a year marked by skyrocketing materials costs and supply chain and labor shortages. Cost and labor savings methods will be discussed in the context of these two unique business models.
Case study of a DOE 2020 Housing Innovation Award winning custom home in a mixed-humid climate that got a HERS 14 with PV, with 3,259 square feet, triple-paned windows, a hydronic radiant floor heating system, an electric vehicle charging station, and 7.3 kW of rooftop-mounted solar panels.
The average American household spends more than $2,200 a year on energy, and heating, ventilating, and air conditioning (HVAC) costs comprise nearly half of the bill. This is one reason why home builders focus on tightening building envelopes to save energy. Yet, limiting the potential for air exchange can negatively impact indoor air quality (IAQ). When outdoor conditions are most extreme during occupied periods, there may be comfort implications from continuing high levels of ventilation during associated weather events. This is true even with heat recovery. To mitigate risks, the Florida Solar Energy Center developed and tested approaches for “smart” ventilation system controls that enable more reliable design, installation, and operation to achieve desired IAQ while also minimizing energy and comfort impacts.
Homeowners and renters on tribal lands have historically faced a disproportionate energy burden compared to the United States as a whole. The Indian Health Service (IHS), which serves these communities, strives to meet aggressive energy performance goals when constructing their residential housing. Challenges common in rural locations can hinder progress toward those goals, such as availability of materials, access to specialized labor, and budget constraints. This guide is for architects and builders who aim to incorporate energy efficiency (EE) into their residential designs. This report presents commercially viable energy efficiency packages for a variety of locations and home inputs to help guide home builders in choosing improvements for energy performance. The intention is to provide a diverse set of packages that can be used during the design phase to achieve energy savings compared to a code minimum building design. By presenting a set of diverse options with similar expected energy savings and life-cycle costs, final decisions can be left up to the building designers who can better determine the appropriate package given local costs, materials, and labor availability. Although this guide was developed for IHS projects, it can be used to help designers and construction professionals better make cost-effective choices when a detailed, project-specific building energy analysis is not possible.
Residential solar and storage markets are growing in the United States. With approximately 1 million new homes constructed every year, this represents a significant opportunity for solar and storage installations. Some homebuilders have begun to build new homes with solar and storage included as a standard offering. It is not clear how solar and storage is incorporated into the new construction process and at what cost. Further, it is unclear what barriers or opportunities exist to scale this model nationwide. To fill this gap in the literature, this research conducts a case study of Mandalay Homes' new solar and storage community in Arizona to gather lessons learned. From this foundation, we further generate a set of pathways to reduce install costs and expand solar and storage market penetration in this sector. To model existing and 2030 solar and storage costs, we use the National Renewable Energy Laboratory's (NREL's) bottom-up cost model. This modeling is further informed by 12 interviews conducted with new home builders, solar contractors, and other subject matter expert organizations. Our case study analysis generated three key considerations for other homebuilders including: 1. Educating local permitting, inspection, and in some cases utility officials on solar and storage products, designs, and code compliant building practices may be required. The need for education may decline as more local governments and utilities review and approve solar and storage projects. 2. Incorporating solar and storage systems into the homebuilding process can add complexity and related coordination challenges. This does not need to result in home construction delays, but can result in costly contractor "dry runs" to construction sites. 3. Deploying solar and storage at the time of new construction has significant economies of scale, which can improve the value proposition of the systems. The case study, extant literature, and interviews were used to model both existing and future solar and storage installation costs at time of new construction. Here, we find three key cost reduction opportunities relating to solar and battery storage hardware, customer acquisition, and overhead. If future contractors can maximize the cost reduction opportunities outlined here, residential new construction costs could decline by 8 - 25% by 2030, depending on the modeled scenario. Though we expect costs to decline through 2030, it is unclear which of these scenarios may ultimately appear. Interviewees further identified a variety of barriers across each cost category that could temper the savings shown here. At the same time, interviewees described several pathways to scale the new construction solar and storage market, beyond installation cost savings. Interviewees confirmed that changes in finance, rate design, resilience policies, deployment mandates, and DER aggregation could all support more market adoption than seen today. These findings suggest that there are significant opportunities to expand new construction markets and this research can serve as a baseline to assess progress in this segment through 2030.
Heat transfer through windows accounts for a significant percentage of a building’s energy use and adds substantially to the peak heating and cooling loads of a home. Over the past 20 years, residential window attachment retrofit technologies have been developed that significantly increase the number of options available to home builders, homeowners, and utilities when considering upgrades of overall window performance. Within the interior window attachments category, honeycomb cellular shades typically have the highest R-values because of their layered or concentric designs. During the winter when the window is fully covered, however, the added insulation reduces the amount of warm indoor air that reaches the window surface, thereby lowering the temperature of the window glass and frame and increasing the potential for condensation to collect on the interior surface of the window. The degree to which this potential is realized depends on the indoor and outdoor conditions as well as the overall thermal resistance of the window and the shades. To examine the condensation buildup potential on the interior surface of the window and the conditions under which this occurs, this report describes experimental research conducted by Pacific Northwest National Laboratory in collaboration with Hunter Douglas, using a a controlled environmental test chamber at the Hunter Douglas facility in Broomfield, Colorado. The results will be used to inform the Attachments Energy Rating Council, which provides energy performance information on all rated window attachments products.
Last year the people of Cleveland, Ohio were troubled by natural gas shortages during one of the coldest winters on record. The severe winter generated a great deal of interest in solar energy as an alternative source of heat. Home owners, home builders and civic officials wanted to know just how much solar energy is available in Cleveland. Now they get a daily report through the city's news media, from information supplied as a community service by NASA's Lewis Research Center. Lewis routinely makes daily measurements of solar energy as part of its continuing research in behalf of the Department of Energy. The measuring device is a sun sensor called a pyranometer (upper photo) located atop a building at the NASA Center. To make the information conveniently available to news media, Lewis developed a Voice Output Integrating Insolometer, an automated system that acquires information from the sun sensor and translates it into a recorded telephone message. The Lewis pyranometer collects sun data for 15 hours daily and measures the total solar energy yield. For reporting to the public, the information is electronically converted to a specific reading. A media representative calling in gets a voice-synthesized announcement of a two or three digit number; the number corresponds to the kilowatt-hours of solar energy that would be available to a typical 500-square-foot solar collector system. Response in Cleveland has been favorable and interest is developing in other parts of the country.
The average American household spends more than $2,200 a year on energy, and heating, ventilating, and air conditioning (HVAC) costs comprise nearly half of the bill. This is one reason why home builders focus on tightening building envelopes to save energy. Yet, limiting the potential for air exchange can negatively impact indoor air quality (IAQ). When outdoor conditions are most extreme during occupied periods, there may be comfort implications from continuing high levels of ventilation during associated weather events. This is true even with heat recovery. To mitigate risks, the Florida Solar Energy Center developed and tested approaches for “smart” ventilation system controls that enable more reliable design, installation, and operation to achieve desired IAQ while also minimizing energy and comfort impacts.
Case study of a DOE 2021 Housing Innovation Award winning custom home in a hot-humid climate that got a HERS -21 with PV, with 1,288 square feet, ENERGY STAR appliances, low-flow fixtures, low-e3 ENERGY STAR windows, LED lighting, six clerestory windows, and solar tubes.
Case study of a DOE 2021 Housing Innovation Award winning custom home in a cold climate that got a HERS -2 with PV, with 2,478 square feet, ground source heat pump, energy recovery ventilator, skylights and clerestory windows, LED lights with motion sensors, and low- and no-VOC paints, cabinets, flooring, and carpet.
Case study of a DOE 2021 Housing Innovation Award winning custom home in a marine climate that got a HERS -22 with PV, with 2,614 square feet, triple-pane windows, LED lighting, and heat recovery ventilator with a HEPA filter and CO2 sensor.
Case study of a DOE 2020 Housing Innovation Award winning custom home in a mixed-humid climate that got a HERS 50 without PV, with 3,680 square feet, ENERGY STAR-labeled appliances, WaterSense-labeled fixtures, and 100% LED lighting.
Case study of a DOE 2020 Housing Innovation Award winning custom home in a cold climate that got a HERS -19 with PV, with 2,538 square feet and a large south-facing roof, which is designed to hold over 80 solar panels, and the large south-facing windows, bringing in sunlight to warm the concrete floors and provide passive solar heating.
Case study of a DOE 2020 Housing Innovation Award winning custom home in a mixed-humid climate that got a HERS -2 with PV, with 2,500 square feet, featuring a novel attic truss specifically designed to accommodate a ducted mini-split heat pump tucked into an insulated chase in the vented attic. The walls are constructed of 2x6 studs installed at 24 inches on center and incorporating advanced framing techniques to reduce the amount of lumber needed and to provide more room for insulation.
Case study of a DOE 2021 Housing Innovation Award winning custom home in a mixed-humid climate that got a HERS 51 without PV, with 1,940 square feet, MERV 13 filters and low-emission paints, adhesives, and carpeting; plus a sealed, conditioned crawl space, and a high-efficiency gas furnace and heat pump.