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Case study of a DOE 2016 Housing Innovation Award winning custom home in a cold climate that got a HERS 2 with PV, with double stud walls, a daylight basement with interior rigid foam, an attic insulated along roof line with R-80 dense-packed fiberglass, an air-to-water CO2 heat pump for radiant floor heat and hot water, and a ductless mini-split heat pump for cooling.
Case study of a DOE 2016 Housing Innovation Award winning affordable home in a marine climate that got a HERS 50 without PV, with SIP walls and roof, an insulated slab on grade, passive solar design, and a ductless heat pump.
Case study of a DOE 2016 Housing Innovation Award winning custom home in a cold climate that got a HERS -11 with PV, with ICF walls, a spray foam-insulated unvented roof, and a ground-source heat pump.
Case study of a DOE 2016 Housing Innovation Award winning production home in a cold climate that got a HERS -5 with PV, with ICF walls, , a spray foam-insulated unvented roof, and a ground-source heat pump.
Driven by a mission to push the leading edge for data center sustainability, NREL recognized the need to make its data center not just energy efficient, but water efficient, too. So, in 2016, NREL, with partners Johnson Controls and Sandia National Laboratories, deployed an innovative thermosyphon cooler (TSC) as a test bed on the roof of the NREL's Energy Systems Integration Facility (ESIF). In combination with existing evaporative towers, the TSC forms an extremely water-and cost-efficient hybrid cooling system.
Case study of a DOE 2016 Housing Innovation Award winning custom home in a cold climate that got a HERS 18 with PV, with graphite enhanced SIPs walls and roof, ICF foundation, passive design, radiant floor heat with solar hot water, HRVs, and triple-pane windows.
Fact sheet describes a Federal Energy Management Program Federal Energy and Water Management Award-winning project that deployed an innovative thermosyphon cooler (TSC) as a test bed on the roof of the National Renewable Energy Laboratory's Energy Systems Integration Facility (ESIF). In combination with existing evaporative towers, the TSC forms an extremely water-and cost-efficient hybrid cooling system.
This article describes the U.S. Department of Energy's Zero Energy Ready Home Program and Housing Innovation Awards. Since 2013, builders around the country have certified over 1,170 homes to the high performance criteria of the DOE Zero Energy Ready Home program. Each year DOE recognizes the best innovators among this group with the DOE Housing Innovation Awards. 2017 winners will be announced at an awards event taking place at the Energy & Environmental Building Alliance (EEBA) high-performance home summit October 10-12, 2017, in Atlanta, Georgia. Twenty-five builders are expected to take home awards and grand award winners in each of the five competition categories will be revealed at the conference. Participating builders represent every climate zone in the country and DOE Zero Energy Ready labeled homes can be found in 34 states. Homes represent the full spectrum of the U.S. construction industry, from affordable to production to custom homes and from single-family detached to duplexes and up to five-story multifamily buildings as well as some retrofit projects have also met the criteria. Every DOE ZER certified home is certified through the ENERGY STAR Certified Homes (Version 3.0, revision 8) program and the U.S. Environmental Protection Agency’s Indoor airPLUS program. Each home must meet the hot water distribution requirements of the EPA’s WaterSense program and the insulation requirements of the 2012 International Energy Conservation Code. If the home has HVAC ducts, they must be installed within the conditioned space of the home. Appliances, exhaust fans, ceiling fans, and most of the lighting should be ENERGY STAR qualified. The DOE Zero Energy Ready Home program also requires homes to have solar electric panels installed or at a minimum to have the conduit and electrical panel space in place for future PV installation, if the home is in a location appropriate for solar power. Homes are constructed with enough energy efficiency built in so that, with a reasonable amount of solar PV panels (i.e., small enough to fit comfortably on the roof), the home could produce enough of its own power to equal the power it uses in a year.
Non-uniform irradiance on the rear-side of bifacial PV systems can cause additional mismatch loss which may not be appropriately captured in PV energy production estimates and software. We have evaluated several rooftop mounted systems over high albedo reflective roofs. Mismatch losses of up to 2% annual loss for very close-mounted (0.15 m) rooftop systems were found, but losses for high ground-clearance rooftop systems were lower (<0.5%). A simplified empirical relationship was found that links the spatial variation of irradiance (specifically the mean absolute difference of irradiance) to the resulting mismatch loss factor, with a R2 fit better than 0.985. This approximate relationship has been validated by experiments on mismatched PV modules, and provides a basis for fast estimation of bifacial mismatch loss factors for use in hourly PV performance simulations such as PVSyst or SAM.
Non-uniform irradiance on the rear-side of bifacial PV systems can cause additional mismatch loss which may not be appropriately captured in PV energy production estimates and software. We have evaluated several scenarios including horizontal single-axis tracking (HSAT) and rooftop mounted systems over high albedo reflective roofs. Mismatch losses of up to 2% annual loss for very close-mounted (0.15 m) rooftop systems were found, but losses for HSAT systems and high ground-clearance rooftop systems were lower (<0.5%). A simplified empirical relationship was found that links the spatial variation of irradiance (specifically the mean absolute difference of irradiance) to the resulting mismatch loss factor, with a R2 fit better than 0.985. This approximate relationship has been validated by experiments on mismatched PV modules, and provides a basis for fast estimation of bifacial mismatch loss factors for use in hourly PV performance simulations such as PVSyst or SAM.
Traditionally, attics have been insulated at the flat ceiling with deliberate venting to manage heat and moisture. Having all the duct air distribution system in the conditioned space is the best building science approach, however this is not always the preferable solution for builders that like to use the roof space for air distribution. Ducts in attics are exposed to very intense heating and cooling conditions. Not only do we have thermal conduction, convection and radiation exchanges occurring but important duct leakage losses that create significant energy balance losses. In the recent IECC 2018 code, deeply buried attics have been credited for reducing the energy losses. Due to the complex thermal performance in each zone adjacent to the buried ductwork these credits seem to be not consistent with the benefits achieve by buring the ductwork in insulation. The thermal performance of buried ducts was examined in both 2-D and 3-D to determine the actual improvement as a function of duct size, duct insulation and attic insulation. In this paper we will describe the field/laboratory and modeling effort undertaken by to quantify the performances of duct systems. Climate zone 2A is included in the field testing, that encompass both hot/dry climates and hot and humid climates. Attics with deeply buried ducts and low air duct leakage had excellent thermal performance and exhibited the best overall thermal performances. Indeed, based on the thermal simulation analysis of deep buried ducts the thermal performance is better than the credit given to them by IRC 2018 code.
This case study describes how a luxury hotel, Bardessono, utilized a major roof-top solar array in its design to achieve significant energy savings and LEED Platinum certification.
This case study describes how Target developed an optimized, re-engineered process that integrates several energy-efficiency measures such as reduced lighting loads, improved roof insulation, optimized ventilation, and more accurate load calculations through its rooftop unit (RTU) replacement program. Target's approach achieved ongoing energy reduction, operations and maintenance reduction, and improved heating, ventilating, and air-conditioning (HVAC) performance by reducing equipment cycling.
This case study describes a multi-site solar photovoltaic (PV) installation project undertaken by BJ’s Wholesale Club. It describes how BJ’s worked with their landlords to overcome the split incentive of the installation, ongoing operational requirements, roof maintenance, and vacancy/turnover at several locations in Massachusetts, Maryland, and New Jersey.
Laboratory facilities are expensive to build and operate, they consume energy at high rates compared to other types of buildings, and modifications are frequently required to accommodate ever-changing research activities. PNNL sought ways to address these issues in the design and construction of a 14,700 sq. ft. new laboratory building. To improve adaptability to change a high roof structure was used that allows raising the ceiling when needed with minimal disruption to installed HVAC and electrical utilities. Also, HVAC equipment was located on a mezzanine above the central corridor rather than above ceilings. This eliminates the need for maintenance personnel to routinely access lab spaces, reducing disruption to research staff and improving maintenance access. To improve the reliability of operations while reducing energy consumption, heat pipe heat recovery with evaporative cooling, zoned heating/cooling coils, high-efficiency condensing boilers, district cooling, VAV fume hoods, DDC controls, energy use monitoring, and implementation of the US Department of Energy’s Guiding Principles for Federal Leadership in Sustainable Buildings were all used. The energy model developed during design projected energy use at 2,840 MBtu/yr, a 13.5% savings over ASHRAE Standard 90.1-2010. The first full year of operation resulted in actual energy use of 2,661 MBtu, a savings of 19% over Standard 90.1. As a result of the project design’s demonstrated success, these strategies will be incorporated into a significantly larger (125,000 sq ft), $65 million lab facility to be constructed on the PNNL campus in 2020.
Driven by dramatic declines in up-front cost, the U.S. solar photovoltaics (PV) industry has taken off over the past decade, growing from 1 gigawatt of installed capacity in 2009 to 89 gigawatts in 2020—or enough capacity to power roughly 19 million homes. The industry is expected to double in size over just the next 5 years.1 Much of the growth has been driven by large, utility-scale projects that can produce 5 mega- watts or more of power—enough to power at least 1,000 homes. The cost of electricity produced by these projects has decreased by more than 70 percent since 2010. As of Q3 2020, development costs of large, util- ity-scale solar PV power plants were under $1 per watt, down by more than 70 percent from 2010.2 A robust array of investors has come forward to efficiently deliver capital to these kinds of utility-scale projects including large banks, insurance companies, pension funds, and others. But low- and moderate-income communities, including communities of color, are at risk of being left behind in the transition to clean energy. Mission- driven solar project developers and financial institu- tions have been working alongside energy justice advocates to open up solar access for these communi- ties, using strategies ranging from community solar, to solar installations on affordable multifamily housing, to distributed solar and storage programs, and more. Their goals go beyond simply generating more green energy to advancing social equity by: • empowering communities to control their energy future • stabilizing energy prices, saving money, and build- ing wealth for low-income families • creating quality jobs • improving health by reducing pollution • providing energy resilience for vulnerable communities Mission-driven actors are successfully deploying a wide variety of strategies to meet these goals, from helping low-income homeowners get solar—and some- times battery storage, to developing solar projects serv- ing affordable rental housing and community facilities, to building larger “shared solar” projects to which households from across the community can subscribe. However, the financing ecosystem does not work nearly as well for these “mission driven” solar proj- ects as it does for utility-scale projects. For home rooftop solar, even if low-income consumers have a home and suitable roof, they may fail to qualify for federal tax incentives, lack adequate credit to qualify for a loan—or the mission-driven lenders seeking to serve them may not be adequately capitalized to make long-term loans. For mission-driven commercial or community-scale projects, assembling nearly every component of the project capital stack—whether bridging early-stage costs, attracting tax credit equity investors, securing long-term debt, or coming up with sponsor equity and filling gaps—can present challenges. A variety of obstacles contribute to the scarcity of financing for low-income solar, including small project sizes, lack of developer balance sheet capacity, both real and perceived issues with credit risk, elevated technical assistance needs, and greater subsidy requirements to pursue goals such as deep energy affordability, climate resilience, or job creation. Still other obstacles are regulatory: for example, not all states allow community solar projects or Power Purchase Agreements, common strategies used for providing low-income solar—and the potential for regulations to shift over time creates risks that mission-driven projects can ill afford. This report synthesizes information garnered from 47 key informant interviews, four focus group discus- sions involving 60 stakeholders, and a review of the substantial existing literature on low-income solar finance to assess the current landscape of mission- driven solar development in the United States, examine the roles that community-based financial institutions could play, and recommend public invest- ments and policy changes that could help to scale the provision of equitable solar finance. Key recommen- dations for policymakers and funders in the renew- able energy and community development fields that emerge from this process include the following: • Help to capitalize and support community-based lenders to provide flexible, low-cost, and long- term financing to mission-driven solar projects— including providing guarantees or other forms of credit enhancement. • Provide federal support for equitable solar, including a grant-in-lieu-of-credits option for the Investment Tax Credit to improve access to this critical government subsidy. • Develop pools of government and philanthropic support that can complement financing from community-based lenders to complete the capi- tal stack for mission-driven projects, as well as to support education and technical assistance to both consumers and potential project sponsors. • Create a national Renewable Energy Credits pro- gram that includes social equity targets to provide a baseline of support for clean energy generation. • Change utility regulations to remove barriers to low-income solar projects; lower permitting costs; provide greater certainty for developers, consumers and owners; and measure progress toward equity in renewable energy policy implementation.
This case study describes how Link Logistics uses community solar programs and other internal procedures to increase NOI at a warehouse property through leasing roof space for solar installation.
Solar energy plays an important role in securing a more resilient, cyber-secure electrical grid in Pennsylvania. Solar's ability to be widely "distributed" on residential and large roofs, marginal lands, and many other locations across Pennsylvania - as opposed to being centralized - offers a strong option for addressing the myriad of potential disruptions that can occur to the grid's infrastructure. And when combined with energy storage, local energy needs can be met immediately without having to wait on the delivery of an off-site fuel source. As more and more distributed solar electricity generation is brought online, researchers, technology developers, solar developers and grid operators are paying close attention to the potential for solar to enhance grid cybersecurity. Although nobody may know when, where, or how the next cyberattack will take place, there are security measures, technical solutions, and management practices that are being implemented across the industry to protect against network control issues and grid operations. Everyone participating in the solar value chain stands to gain from a coordinated, iterative approach to protect against cyber vulnerabilities and build deeper resilience into the architecture of our grid.