Net zero energy is a concept of energy self-sufficiency based on minimized demand and use of local renewable energy resources. A net zero energy military installation is defined as: “A military installation that produces as much energy on-site from renewable energy generation or through the on-site use of renewable fuels, as it consumes in its buildings, facilities, and fleet vehicles.” [1] The National Renewable Energy Laboratory (NREL) developed a comprehensive, first-of-its-kind strategy for evaluating a military installation’s potential to achieve net zero energy status, including an assessment of baseline energy use, energy use reduction opportunities from efficiency or behavior changes, renewable energy generation opportunities, electrical systems analysis of renewable interconnection, microgrid potential, and transportation energy savings. This paper describes NREL’s net zero energy assessment strategy and provides a planning guide for other organizations interested in evaluating net zero potential. We also present case studies and describe lessons learned from NREL’s net zero energy assessments at seven installations, including the importance of enforcing and funding mandates, providing leadership support, collecting accurate data, and selecting appropriate technologies. Finally, we evaluate whether the net zero concept is a useful framework for analyzing an energy strategy and a reasonable goal.

Until recently, large-scale, cost-effective net-zero energy buildings (NZEBs) were thought to lie decades in the future. However, ongoing work at the National Renewable Energy Laboratory (NREL) indicates that NZEB status is both achievable and repeatable today. This paper presents a definition framework for classifying NZEBs and a real-life example that demonstrates how a large-scale office building can cost-effectively achieve net-zero energy. The vision of NZEBs is compelling. In theory, these highly energy-efficient buildings will produce, during a typical year, enough renewable energy to offset the energy they consume from the grid. The NREL NZEB definition framework classifies NZEBs according to the criteria being used to judge net-zero status and the way renewable energy is supplied to achieve that status. We use the new U.S. Department of Energy/NREL 220,000-ft 2 Research Support Facilities (RSF) building to illustrate why a clear picture of NZEB definitions is important and how the framework provides a methodology for creating a cost-effective NZEB. The RSF, scheduled to open in June 2010, includes contractual commitments to deliver a Leadership in Energy Efficiency and Design (LEED) Platinum Rating, an energy use intensity of 25 kBtu/ft 2 (half that of a typical LEED Platinum office building), and net-zero energy status. We will discuss the analysis method and cost tradeoffs that were performed throughout the design and build phases to meet these commitments and maintain construction costs at $259/ft 2 . We will discuss ways to achieve large-scale, replicable NZEB performance. Many passive and renewable energy strategies are utilized, including full daylighting, high-performance lighting, natural ventilation through operable windows, thermal mass, transpired solar collectors, radiant heating and cooling, and workstation configurations allow for maximum daylighting. This paper was prepared by the client and design teams, including Paul Torcellini, PhD, PE, Commercial Building Research Group Manager with NREL; Shanti Pless and Chad Lobato, Building Energy Efficiency Research Engineers with NREL; David Okada, PE, LEED AP, Associate with Stantec; and Tom Hootman, AIA, LEED AP, Director of Sustainability with RNL.

The Town of Avon Colorado and the Eagle River Water and Sanitation District have partnered to design, construct, and operate a mechanical “Community Heat Recovery System” which extracts low-grade waste heat from treated wastewater and delivers this heat for beneficial use. Immediate uses include heating of the community swimming pool, melting snow and ice on high pedestrian areas in an urban redevelopment zone in order to improve pedestrian safety, and space heating for project buildings and an adjacent water plant pump station building. Points of use are located within one mile of the treatment plant. The initial system is sized to extract heat from 170 m 3 /hr (1.08 mgd) of wastewater plant effluent with a 298 kW (400 hp) heat pump. The heat pump will deliver 1,026 kW (3,500,000 BTU/hr) energy to the heat recovery system. A supplemental natural gas boiler provided to meet peak demands will provide an additional 1,026 kW (3,500,000 BTU/hr) energy. The system is expandable allowing the installation of a second heat pump in the future and roof-mounted solar thermal panels. Power for the waste heat recovery system is provided by wind-generated electricity purchased from the local electric utility. The use of wind power with an electric-powered heat pump enables the agencies to fulfill energy needs while also reducing the carbon footprint. The system will achieve a reduction in the temperature of the treated wastewater, which is currently discharged to the Eagle River during low river flow, fish-sensitive periods. The agencies expect to save tax payers and rate payers money as a result of this project as compared to other alternatives or the status quo because it results in a more sustainable long-term operation. At 2008 utility commodities pricing, delivery of heat generated from this system was estimated to cost about one-third less than that from a conventional natural gas boiler system. This facility is the first of its kind in the U.S. and received a “New Energy Community” grant from the State of Colorado. This project shows how local agencies can work cooperatively for mutual benefit to provide infrastructure which accommodates growth and urban renewal and simultaneously demonstrate strong environmental leadership. The potential application of this technology is broad and global. The installed system is expected to cost about $5,000,000; construction will be completed in 2010.

This paper deals with the construction and implementation of the Off-Grid Zero Emissions Building (OGZEB), a project undertaken by the Energy Sustainability Center (ESC), formally the Sustainable Energy Science and Engineering Center (SESEC), at the Florida State University (FSU). The project involves the design, construction and operation of a completely solar-powered building that achieves LEED-NC (Leadership in Energy and Environment Design-New Construction) platinum certification. The 1064 square foot building is partitioned such that 800 square feet is a two bedroom, graduate student style flat with the remaining 264 square feet serving as office space. This arrangement allows the building to serve as an energy efficient model for campus designers in student living and office space. The building also serves as a prototype for developing and implementing cutting edge, alternative energy technologies in both residential and commercial settings. For example, hydrogen is used extensively in meeting the energy needs of the OGZEB. In lieu of high efficiency batteries, the excess electricity produced by the buildings photovoltaic (PV) panels is used to generate hydrogen via water electrolysis for long term energy storage. The hydrogen is stored on-site until needed for either generating electricity in a Proton Exchange Membrane (PEM) fuel cell stack or combusted in natural gas appliances that have been modified for hydrogen use. The use of hydrogen in modified natural gas appliances, such as an on-demand hot water heater and cook top, is unique to the OGZEB. This paper discusses the problems and solutions that arose during construction and includes detailed schematics of the OGZEBs energy system.

As an increasing number of buildings aspire to significant energy reduction and higher Leadership in Energy and Environmental Design (LEED®) certifications, it is clear that non-regulated process loads are the single greatest remaining opportunity in high performance design. Historically outside the purview of state and national energy design standards, the performance of transformers, elevators, escalators, process systems, and consumer information technology underscore a significant challenge and rising opportunity. This paper examines the impact of non-regulated loads on high performance buildings, ranging from first cost to energy performance and occupant behavior.

Pulte Homes, a production home builder and community developer partnering with the U.S. Department of Energy’s Building America program, has collaborated with the Center for Energy Research at the University of Nevada, Las Vegas, and NV Energy, the local electric utility, on an energy conservation project in the Las Vegas Valley. This study entails four model homes at a new development named Villa Trieste, located in the Summerlin community of Las Vegas. The models, ranging in floor plan area from 1,487 to 1,777 square feet, have been constructed under the Environments for Living program and have been platinum certified by LEED (Leadership in Energy and Environmental Design) for Homes. According to the Home Energy Rating System Index, all four models are over 50% more efficient than homes of equal size built to 2006 International Energy Conservation Code standards. The study focuses on the cost benefit of installing additional efficiency upgrades in future homes at the development. Though all proposed upgrades offer reductions in energy use, many offer little improvement relative to their installation costs. Higher-efficiency windows, heat recovery ventilators, and R-36 spray foam attic insulation have been deemed appropriate measures for future homes. All homes are to be equipped with photovoltaic arrays; increasing the size of the arrays will cost-effectively reduce net energy consumption.

Building a zero energy home requires several major considerations: site selection for the home; considerations to use less; conservation of what you produce; and evaluation the best choices of renewable resources. This paper discusses the use of climate data collection software, heat loss and heat gain considerations and software; how to achieve a zero energy building and qualifying as a LEED (Leadership in Energy and Environmental Design) Certified Platinum home. Site selection is the first step. This first step can be taken after you have identified your goals. What alternative energy systems do you want to use? Do you want to use more than one alternative source? What other site considerations are important? In my case, I wanted to use solar energy as my primary alternative energy source. Why? I want comfort, reliability and ease of use. Other alternatives may require more maintenance. Wind power will be a second source that will be incorporated to produce electricity when the PV system can not produce. The site selected is a south facing mountain that has a steady breeze most of the time. Another consideration for me is the ability to use earth-sheltering as a measure of high efficiency construction. The south-facing mountain also provides the opportunity to “nestle” into the mountainside. Calculations and basis of design are presented. Using less is a key mindset that we all need to move toward. Using less does not mean that you suffer. This house will be comfortable year round with little effort because the house uses passive solar design for lighting and space heating, active solar hot water for additional heating of the floor and domestic hot water, and PV/wind/biodiesel generator backup to generate electricity for lighting and other typical electrical loads. The construction materials provide high R-values and green products that contribute to excellent indoor air quality. SIPs (Structural Insulated Panels) will be used as the structural components for the walls and roof. All electrical appliances, refrigerator, lighting, and washer/dryer were selected to use less electricity and water. Data describing the energy requirements are provided. Reuse all that you can. I am incorporating a masonry heater, also known as a Russian Fireplace. The combustion efficiency of the masonry fireplace is typically 92–94 percent with very low emissions. The masonry fireplace will provide passive mass for passive release of the woodburning energy during the evening and heat hot water coils in the fireplace as well (as the hot water backup system). The use of hard woods from the land will provide heat overnight, heat for cooking and supply additional BTUs for domestic hot water and radiant heat. Many of the building materials that are selected for construction are from the land; stone and whole cut wood from the land will be used for esthetic appeal and thermal mass thereby reducing harmful manufacturer’s emissions. My site is an excellent site for a hybrid solar and wind power (with a biodiesel generator as backup) system. The orientation and wind profile of the land is optimal for solar and wind energy applications. Site specific data and optimization of active solar, passive solar and PV/wind systems are presented. Life cycle costs are presented to show the cost comparison using Years-to-Payback and Return on Investment approaches for the energy systems and LEED certification costs for new construction.

This paper deals with the Off-Grid Zero Emissions Building (OGZEB), a project undertaken by the Sustainable Energy Science & Engineering Center (SESEC) at Florida State University (FSU). The project involves the design, construction and operation of a completely solar-powered building that achieves LEED-NC (Leadership in Energy and Environment Design-New Construction) platinum certification. The resulting 1000 square foot building will be partitioned such that 750 square feet will be a two bedroom, graduate student style flat with the remaining 250 square feet serving as office space. This arrangement will allow the building to serve as an energy efficient model for campus designers in student living and office space. The building will also serve as a prototype for developing and implementing cutting edge, alternative energy technologies in both residential and commercial settings. For example, hydrogen will be used extensively in meeting the energy needs of the OGZEB. In lieu of high efficiency batteries, the excess electricity produced by the building’s photovoltaic (PV) panels will be used to generate hydrogen via water electrolysis. The hydrogen will be stored on-site until needed for either generating electricity in a Proton Exchange Membrane (PEM) fuel cell stack or combusted in natural gas appliances that have been modified for hydrogen use. Although commercial variants already exist, a highly efficient water electrolysis device and innovative PEM fuel cell are currently under development at SESEC and both will be implemented into the OGZEB. The use of hydrogen in modified natural gas appliances, such as an on-demand hot water heater and cook top, is unique to the OGZEB.

Cooling, Heating and Power (CHP) systems are a form of distributed generation that uses internal combustion prime-power engines to generate electricity while recovering heat for other uses. CHP is a promising technology for increasing energy efficiency through the use of distributed electric and thermal energy recovery-delivery systems at or near end-user sites. Although this technology seems to be economically feasible, the evaluation and comparison of CHP systems cannot be restricted to economical considerations only. Standard economic analysis, such as life cycle economic analysis, does not take in consideration all the benefits that can be obtained from this technology. For this reason, several aspects to perform a non-conventional evaluation of CHP systems have to be considered. Among the aspects to be included in a non-conventional evaluation are: power reliability, power quality, environmental quality, energy-efficient buildings, fuel source flexibility, brand and marketing benefits, protection from electric rate hikes, and benefits from promoting energy management practices. Some benefits of these non-economical evaluations can be transferred into an economic evaluation but others give intangible potential to the technology. This paper focus on a non-conventional evaluation based on energy-efficient buildings, which is associated to energy conservation and improvement of the building energy performance rating for government energy programs like Energy Star and Leadership in Energy and Environmental Design (LEED). Results show that the use of CHP systems could improve the Energy Star Rating in more than 50 points. The Energy Star Rating is significant on the LEED Rating as a building can score up to 10 points of the 23 available in the Energy & Atmosphere category on energy efficiency alone. As much as 8 points can be obtained in this category due to the Energy Star rating increment from the use of CHP systems. Clearly the use of CHP systems will help building owners to reach the benefits from these energy programs while improving the overall energy use and energy cost.