Search

Existing building energy use plays a significant role in achieving climate action goals for governments and organizations. In the United States, over 30 cities/counties and three states have enacted benchmarking or energy efficiency ordinances for existing buildings. ASHRAE Standard 100, Energy Efficiency in Existing Buildings, provides a methodology for authorities aiming to increase the energy efficiency of their existing building stock through the use of best operation and maintenance procedures, evaluation of actual building energy use, and energy audits that require proven energy performance improvements. Standard 100 includes a table of target energy use intensities (EUIs) that can be used as an energy efficiency evaluation method within the Standard. This paper uses actual building energy use data from publicly available benchmarking disclosures to evaluate how real existing buildings compare to Standard 100's energy targets. The paper uses energy data from over 10,000 buildings located in major cities across the U.S. and examines both site and source EUI targets as well as the 25th percentile and alternative 40th percentile targets from Standard 100. [ABSTRACT FROM AUTHOR]

ASHRAE Standard 100, Energy Efficiency in Existing Buildings, is an ASHRAE Standard aimed at increasing existing building energy efficiency through the use of best operation and maintenance procedures, evaluation of actual building energy use, and verified energy performance improvements. Most buildings seeking compliance with Standard 100 must compare their energy performance with established energy use intensity (EUI) targets. Under Standard 100, buildings that do not already meet their designated EUI target are required to conduct an energy audit, implement efficiency measures, and prove that their new EUI meets the target. While Standard 100 allows for local jurisdictions to develop their own EUI targets, it also provides a table of default energy targets for commercial buildings that are based on the Commercial Building Energy Consumption Survey (CBECS) and energy modeling. This paper derives localized Standard 100 EUI targets for 11 United States cities across 7 climate zones using local benchmarking data collected through annual building energy benchmarking ordinances. These localized targets were compared to the default energy targets available in Standard 100. Nearly half of the targets developed were within 20% of the default ASHRAE Standard 100 energy targets. Large differences between the default and localized targets indicate that (1) localized development of energy performance targets can better align building performance targets with energy efficiency or greenhouse gas emissions goals, and (2) the default Standard 100 energy targets may benefit from future refinements. [ABSTRACT FROM AUTHOR]

Single-duct variable-air-volume (VAV) systems are widely used to condition buildings in the United States. When such a system serves multiple zones with different load profiles, simultaneous cooling and heating frequently occur. To avoid this inefficient scenario, dual VAV systems, where one VAV system provides cooling and the other provides heating, could be used. This paper proposes a new configuration for dual VAV systems to improve their operation to reduce the loads on cooling and heating equipment and thereby total energy use. The proposed configuration and its sequence of operation can reduce cooling and heating loads by eliminating simultaneous heating and cooling and maximizing the use of outdoor air (OA) for cooling and return air for heating. The performances of both single and dual VAV systems are simulated for given buildings and for different locations to estimate load reductions and fan energy savings achieved by the proposed dual VAV system configuration and control strategies. The simulation results that show significant heating load reductions of up to 89%, great fan savings up to 15%, and minor cooling load reductions of around 1% can be obtained, depending mainly on load variations and locations. [ABSTRACT FROM AUTHOR]

In general, U.S. municipal and state benchmarking and disclosure programs have proven effective in encouraging the development of a strong market for building energy efficiency. Available data for select cities in the United States shows that energy savings per unit of floor space for these programs range between 6% and 8% over a two-year period (Pan et al. 2016, 10). Despite the merit of these programs, however, several shortcomings have been identified, including the need for: (1) more efficient and cost-effective assessment of buildings for retrofit opportunities, and (2) greater standardization and automation of the benchmarking and disclosure processes. To address these shortcomings, Lawrence Berkeley National Laboratory, Johnson Controls, and ICF International are developing a free, on-line, open-source, building energy efficiency upgrade targeting tool. The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) Inverse Modeling Toolkit (IMT), and Johnson Controls' LEAN Energy Analysis, serve as the technical basis for the tool, which will automatically regress monthly energy usage versus ambient temperature; compare model coefficients to quantify energy and cost-savings potential; and analyze model coefficients to identify energy conservation measures (operational or equipment) for a single building or portfolio. The tool is unique in its open-source, modular, online, and 100% automated format. The source code will be published on GitHub and thus available for use and modification by the buildings community. This paper discusses: (1) the market's need for the tool; (2) the tool's analytic methodology, based on a combination of ASHRAE's IMT and LEAN Energy Analysis; (3) tool innovations with industry impact, including a fully automated approach for building change-point selection; (4) and the outcomes of early pilot applications of the tool among 36 hotel buildings. Future work and potential applications are also discussed. [ABSTRACT FROM AUTHOR]

This paper describes a real life project conducted by the Pacific Northwest National Laboratory (PNNL) and PNC Financial Services Group's design team. This is a demonstration project supported by the U.S. Department of Energy's Commercial Partnerships Program. The goal of this project is to design and construct a net-zero energy bank branch in Fort Lauderdale, Florida. The integrated design involved two steps, 1) achieve 50% better energy performance than comparable baseline building, i.e., ANSI/ASHRAE/IESNA Standard 90.1-2004, using the optimized energy efficiency measures (EEMs), 2) then use renewable to cover the remaining energy loads. The lessons learned from this process will be used in the development of all future PNC Branches in the United States. At the concept design phase, the EnergyPlus models were developed to evaluate the EEMs and optimize the design package in terms of energy savings and cost-effectiveness. Despite a comprehensive EEM package, the total energy reduction was only 27% over the baseline. This result turned the team's attention back to PNNL's metering analysis, which revealed that over 50% of energy consumption in a similar branch was contributed from decorative lighting and plug loads. This metering study also revealed a substantial amount of base load existed during business off-hours. Another set of EEMs were proposed to tackle the newly found sources of energy consumption. Exterior lighting was reduced by using LED fixtures for site lighting, signage and decorative lights, and plug loads were reduced by combining ENERGY STAR equipment with off-hours turn off of major equipment. PNC showed great commitment by actively engaging their IT department. The collaboration efforts made it possible to find a solution to tackle the plug loads and save additional 16,000 kWh of electricity. With these changes, the total building energy consumption dropped to 56% of the baseline building consumption, exceeding the target. This paper presents how metering data was used to calibrate models and apply the calibrated modeling analysis results to guide the design team throughout the project design phases. The case study showed the importance of metering and studying the actual energy end use distribution in a building. It also served as a showcase for what is possible when there is commitment from the client and great rapport between design teams. [ABSTRACT FROM AUTHOR]

Data centers account for 1.5% of the energy consumption in the United States according to a recent report by the Environmental Protection Agency. These facilities' IT power and cooling requirements may increase in the future, especially with the rise of cloud computing and increased heat densities of servers. Since most utility power is generated by burning coal or fossil fuel, innovation is essential to meet the challenge of providing sustainable cooling and power for data centers. This paper proposes using Hydrothermal Energy for data centers whereby cooling and power are both sustainably generated. Coastal communities that have nearby cold and warm water resources are candidates for future data centers that can be operated completely off the grid while absorbing carbon from the atmosphere. The paper acknowledges that, while there are still challenges to be met in designing these facilities, Hydrothermal Net-Zero Energy data centers are within the realm of possibility. [ABSTRACT FROM AUTHOR]

A recent report by the U.S. Environmental Protection Agency (EPA 2007) indicates that data centers now account for approximately 1.5% of energy consumption in the United States, with energy consumption expected to double by 2013. In addition, newer energy codes such as ASHRAE standard 90.1, 2010 require even greater efficiency requirements, now placing data centers under the code for the first time in history, requiring many data centers to have some sort of economizer. As the focus for data centers have been primarily on energy efficiency, the building industry as a whole has been moving towards more sustainable practices for overall improvement of the environment. LEED (Leadership in Energy and Environmental Design developed by the USGBC) criteria for data centers is currently under development. One part of that criterion is water conservation and the collection of rainwater and cooling coil condensate. Water is increasingly becoming more of a concern for all facilities and is expected to rival power use in the future for cost and availability. The purpose of this paper is to identify how water conservation, primarily the use of rainwater for the data centers can help increase the efficiency of the data center, thereby lowering its PUE, reduce the water required at the facility, and reduce the amount of water utilized at the regional power plant. This process lowers the water required for the entire region, a win-win situation. This paper will also describe how these systems can be utilized in lieu of some of the newer code required economizers where standard air and waterside economizers are impractical for various reasons. [ABSTRACT FROM AUTHOR]

This paper compares HVAC simulations between EnergyPlus and DOE-2.2 for data centers. The HVAC systems studied in the paper are packaged direct expansion air-cooled single zone systems with and without air economizer. Four climate zones are chosen for the study - San Francisco, Miami, Chicago, and Phoenix. EnergyPlus version 2.1 and DOE-2.2 version 45 are used in the annual energy simulations. The annual cooling electric consumption calculated by Energy- Plus and DOE-2.2 are reasonably matched within a range of -0.4% to 8.6%. The paper also discusses sources of differences between EnergyPlus and DOE-2.2 runs including cooling coil algorithm, performance curves, and important energy model inputs. [ABSTRACT FROM AUTHOR]

Ideally, whole-building energy simulation programs model all aspects of a building that influence energy use and thermal and visual comfort for the occupants. An essential component of the development of such computer simulation models is a rigorous program of validation and testing. This paper describes a methodology to evaluate the accuracy of whole-building energy simulation programs. The methodology is also used to identify and diagnose differences in simulation predictions that may be caused by algorithmic differences, modeling limitations, coding errors, or input errors. The methodology has been adopted by ANSI/ASHRAE Standard 140, Method of Test for the Evaluation of Building Energy Analysis Computer Programs (ASHRAE 2001α, 2004). A summary of the method is included in the 2005 ASHRAE Handbook—Fundamentals (ASHRAE 2005). This paper describes the ASHRAE Standard 140 method of test and its methodological basis. Also discussed are possible future enhancements to ASHRAE Standard 140 and related research recommendations. [ABSTRACT FROM AUTHOR]

Building operations account for approximately 40% of US energy use and carbon emissions, and vapor compression cycles are the primary method by which refrigeration and airconditioning systems operate. Representing a significant portion of commercial and residential building energy consumption, vapor compression cycles are a target for improvement in efficiency and savings. This paper presents a data-driven approach to find the optimal operating conditions of single- and multievaporator systems to minimize energy consumption while meeting operational requirements such as constant cooling or constant evaporator outlet temperatures. The problem lies in the development of a control architecture that will minimize the energy consumed without requiring any models of the system or expensive mass flow sensors. The application of the presented approach improves efficiency and is demonstrated in simulation and on an experimental system. [ABSTRACT FROM AUTHOR]

Water heating accounts for 24% of residential natural gas use in the U.S. Yet very few data are available on how hot water is actually used in homes. Better data on hot water usage can help manufacturers, energy program designers, and policy makers design better products, programs, and policies to reduce energy and water use and improve water heating performance. This paper provides high-resolution data on draw volume, length, flow rate, and spacing both overall and by hot water end use. It is based on data collected in ten homes in the Minneapolis/ St. Paul metro area in 2009-2010. Data were collected in each home using both storage and tankless water heaters. Daily hot water consumption varied by household size but averaged 38 gallons (range of site averages 20-59 gallons). It was not affected by water heater type. The number of draws per day averaged 226 (range 47 to 1080). On average only 26 of these draws lasted 5 seconds or longer (range 8 to 48). The average draw of 5 seconds or more used 1.4 gallons of hot water and lasted 61 seconds. These draw patterns differ significantly from the assumptions implicit in current residential water heater rating methods. For 91% of draws, no hot water reached a fixture. These draws account for 11% of total draw volume. Draws for which hot water actually reached a fixture accounted for 9% of all draws, 73% of draws five seconds or greater, and 89% of total hot water volume used. These were broken down into draws where only a single fixture was active (8% of all draws, 71% of draws >= 5 seconds, and 78% of hot water volume) and draws where more than one fixture was active (0.3% of all draws, 2% of draws >=5 seconds, and 11% of total hot water volume). Showers and baths accounted for 8% of single fixture draws but 41% of total HW volume. Kitchen sinks accounted for 51% of single fixture draws and 18% of volume. Bathroom sinks accounted for 28% of single fixture draws and 11% of volume. Clothes washing accounted for 12% of single fixture events and 9% of total hot water volume. Dishwashers accounted for 4% of the events and 1% of hot water volume in sites that used dishwashers. 11% of hot water volume went to multiple fixtures at once, and the remaining 11% (or 7% in sites with dishwashers) of hot water volume never reached a hot water fixture. Hot water use showed morning and evening peaks with the morning peak later on weekends than weekdays. [ABSTRACT FROM AUTHOR]

The U.S. Army Corps of Engineers, in collaboration with the U.S. Department of Energy's (DOE) National Renewable Energy Laboratory (NREL), academia, and private sector subject matter experts, recently completed an energy study to evaluate potential site and source energy-use reduction in new Army buildings. The study was completed in response to the mandates for energy savings in federal buildings enacted by the U.S. Energy Independence and Security Act of 2007 (U.S. Congress 2007). The building types studied included an Unaccompanied Enlisted Personnel Housing (UEPH or barracks), a brigade headquarters (administrative building), a company operation facility, a maintenance facility, and a dining facility (DFAC). The study was conducted for representative locations in all 15 DOE identified climate zones in the United States with building designs adapted to these climatic conditions. This paper presents the results of the energy analysis for a typical Army dining facility. It discusses energy efficiency measures and combinations used to reduce both internal and external loads on the building and overall energy use. The largest load in a DFAC is the cooking, and the currently available best-in-class kitchen equipment is included in the final design. The potential site energy savings compared to the energy code range from 21% to 38%. The potential source energy savings compared to Commercial Building Energy Consumption Survey ranges from 37% to 42%. Additional savings may be obtained if an efficient cogeneration system is used and the building is considered as a part of the building cluster or community to fully utilize the energy from the cogeneration system. [ABSTRACT FROM AUTHOR]

The Army is required by law (EPACT 2005, EISA 2007) to eliminate fossil fuel use in new and renovated facilities by 2030 and to reduce overall facility energy usage by 30% by 2015. Army policy is to achieve eight net zero energy pilot installations by 2020, 25 net zero energy installations by 2031, and for all installations to achieve net zero energy status by 2058. Achieving Net Zero Energy (NZE) will only be possible if an optimum mix of demand reduction and renewable sources are put in place at a community (installation) or building cluster scale. The Army operates what are essentially small campuses, or clusters of buildings on its installations. The US Department of Energy (DOE) is focused on the national grid scale or on individual buildings, while the commercial focus is on retrofits to individual buildings. There are only few case studies worldwide that address dynamics of energy systems at the community scale, and to date, there is a lack of tools to perform that task. The building stock at most US Army installations is complex and includes a mix of high and low energy use buildings. Energy use in these buildings varies due to the different military mission and requirements for each building, installation growth and expansion, and soldier deployment. Achieving net zero energy economically at such installations will require a seamless blend of energy conservation in individual buildings and building systems automation, utility management and control, and power delivery systems that have the capability to offer integration of on-site power generation (including renewable energy sources). This paper describes the Net Zero fossil fuel based energy optimization process and illustrates it with an example based on the results of study conducted for a cluster of buildings at Fort Irwin, CA. The integrated optimization process is being developed under the Army research and development project "Modeling Net Zero Installations - Energy (NZI-E)" and the International Energy Agency (IEA) Energy Conservation in Buildings and Community Systems (ECBCS) Annex 51. The process is stepped, beginning with the optimization of each building to achieve the most cost effective energy efficient optimization of building envelope and energy using systems. Then energy saving measures affecting the total building cluster are optimized taking advantages of the diversification between energy intensities, scheduling, and waste energy streams utilization. The energy demands of the resulting energy-use optimized cluster will require the minimum sized renewable energy system needed to make the building cluster Net Zero fossil fuel energy. [ABSTRACT FROM AUTHOR]

This paper explores the laboratory performance of five integrated Heat Pump Water Heaters (HPWHs) across a wide range of operating conditions representative of US climate regions. Laboratory results demonstrate the efficiency of this technology under most of the conditions tested and show that differences in control schemes and design features impact the performance of the individual units. These results were used to understand current model limitations, and then to bracket the energy savings potential for HPWH technology in various US climate regions. Simulation results show that HPWHs are expected to provide significant energy savings in many climate zones when compared to other types of water heaters (up to 64%, including impact on HVAC systems). [ABSTRACT FROM AUTHOR]

According to DOE's Commercial Buildings Energy Consumption Survey (CBECS), the average energy use for all existing U.S. buildings has essentially remained flat since the early 1980s at about 88,000 Btu/ft² (277.4 kW/m²) despite public and private initiatives that resulted in increased standards and improved components. Furthermore, 98% of all buildings are less than 100,000 ft² (9,290 m²) with the distribution heavily weighted to buildings between 25,000 and 50,000 ft² (2,323 and 4,645 m²). The Greater Philadelphia Innovation Cluster (GPIC) for Energy Efficient Buildings, a Department of Energy Hub, has examined existing buildings, regulations, policies, and current retrofit practices in the ten counties including and surrounding Philadelphia. This paper will provide details of barriers to energy efficiency retrofits of small and medium sized buildings and suggest market and technology pathways forward. [ABSTRACT FROM AUTHOR]

Data Centers are an ever increasing user of energy in our economy. While the performance per watt of our IT equipment continues to increase exponentially, this energy performance improvement is still outstripped by increasing demand. Because of this, the efficiency of data centers must continue to improve. Beyond just efficiency, many data centers now are working towards reuse of their waste energy in other areas in the data center or on the site or campus. How to account for this, through metrics and measurements, is the topic of this paper. The Energy Reuse Effectiveness metric or ERE is discussed; both the development and application of the metric are looked at in detail. The use of ERE in conjunction with PUE (Power Usage Effectiveness) is also considered. [ABSTRACT FROM AUTHOR]

The efficient use of energy reduces both energy costs and greenhouse gas (GHG) emissions, and the mix of energy sources can also affect GHG emissions. In the United States, the building sector comprises about one third of GHG emissions [1], presenting an attractive opportunity for utilizing advanced design, operation and control strategies to minimize energy consumption and emissions while optimizing overall system performance through the implementation of cogeneration, heat recovery, adaptive controls and other advanced techniques. This paper presents an approach for controlling GHG emissions and energy consumption through improved communication between energy consumers and suppliers, and advanced energy management systems. A specific example involving cogeneration is detailed to demonstrate the concept. [ABSTRACT FROM AUTHOR]

The 2005 Energy Policy Act Requires that federal facilities be built to achieve at least a 30% energy savings over the 2004 ASHRAE Standard 90.1-2004. The Construction Engineering Research Laboratory of the U.S. Army Corps of Engineers, in collaboration with U.S. Army Corps of Engineers Headquarters and centers of standardization for respective building types, the U.S. Department of Energy (DOE), the National Renewable Energy Laboratory, and the ASHRAE Military Technology Group have developed design guides to achieve 30% energy savings over a baseline built to the minimum requirements of ASHRAE Standard 90.1-2004 for new buildings to be constructed under the Military Transformation Program. The building types included barracks, administrative buildings (e.g., a battalion headquarters and a company operation facility), a maintenance facility, a dining facility, a child development center, and an Army reserve center. This paper presents the results of the energy analysis for tactical equipment maintenance facilities (TEMFs). It provides a definition of the baseline building selected for the analysis and the modeling assumptions. As a result of a computer analysis using EnergyPlus version 2.0, baseline and target energy budgets are clearly defined for all 15 DOE climate zones. Finally, a recommended set of energy efficiency solutions for each climate zone is presented that enable at least 30% energy savings in addition to improved and more productive work environments that provide better thermal conditions and indoor air quality for soldiers and workers. Results of this study were implemented through the Army's standard design/build process in late 2007 by incorporating the target energy budgets by climate zone and the recommended sets of technologies to meet these budgets into the Army standard Request for Proposal for TEMFs. [ABSTRACT FROM AUTHOR]

In this paper, the results a series of sensitivity analyses are presented and discussed to assess the impact of the selection methodology to generate a typical weather year suitable for energy analysis of building systems. In particular, the impact of weighting factors associated with various weather variables was investigated. Moreover, the effect of the length of recorded data used to generate the typical year was evaluated. The analysis is carried out for 10 US sites for which measured weather data are reported for at least 30 years. The results indicate that using the TMY2 selection approach it was better to assign more weight to global solar radiation than to direct normal radiation and that 15 years of recorded data would be sufficient to generate a typical weather year. [ABSTRACT FROM AUTHOR]

With the issuing of the recent Environmental Protection Agency (EPA) report to Congress (EPA, 2007), the issue of data center energy consumption is now a matter of intense industry focus. Key findings of the EPA report are that most data centers do not know what their energy efficiency is, and an equal number do not even know how to go about measuring such energy efficiency. Knowledge of a data center's energy efficiency is now considered a competitive advantage by many world-class companies. With funding from the Department of Energy, the Pacific Northwest National Laboratory (PNNL) has established its Energy Smart Data Center Test Bed (ESDC-TB), which is housed in a mixed-use facility. In the latest phase of this effort, PNNL has undertaken a major effort to instrument its ESDCTB, and the supporting facility, in order to quantify the energy efficiency of information technology (IT) equipment and infrastructure Under Test (ITUT), in real-time. In addition, PNNL has created a comprehensive software tool, FRED, to acquire, reduce, and display the power consumption of the various parts of the ESDC-TB and the supporting facility in real-time. FRED will soon have the capability to calculate and display the real-time energy efficiency of ITUT - the energy efficiency metric of choice is The Green Grid's Data Center Infrastructure Efficiency (DCiE). This paper describes these capabilities in detail and also describes how to quantify the ITUT's share of the total power consumption for major subsystems such as its facility chiller plant. [ABSTRACT FROM AUTHOR]

This paper summarizes the results of an investigation to assess the impact of solar models used to estimate hourly global, diffuse, and direct solar radiation on annual building energy use. The building energy analysis is carried out by detailed whole-building simulation tools that used hourly Typical Meteorological Year (TMY) weather files. Annual energy use for prototypical office buildings with various geometric aspect ratios and window-to-wall ratios was obtained for several tropical sites. Nonsolar weather data for the same sites were obtained from the National Climatic Data Center (NCDC). Moreover, one-year TMY-formatted weather files developed from predictions of solar radiation from four models and from measured data are used in the analysis to determine the effect of the solar model on the annual energy use of prototypical office buildings. The four models include the Kasten model, Muneer model, Zhang and Huang model, and neural network-based model. The results of the analysis indicate that the Zhang and Huang model, when used with site-fitted coefficients, outperforms the neural network model and the Kasten model for accurately predicting annual building energy use. [ABSTRACT FROM AUTHOR]

Having building energy simulation programs with the inherent capability to efficiently perform optimization either during the conceptual design phase or during the operational stage would provide professionals with a tool to reduce energy use in building systems. This paper starts by reviewing two popular simulation techniques for building energy systems—sequential component method (SCM) and equation-oriented method (EOM)—in terms of their advantages and disadvantages. Next, a hybrid simulation strategy, successive approximation method (SAM), is proposed, This strategy is inherently capable of dealing with both design and optimal operation while combining desirable features of both SCM and EOM. SAM is a more coherent strategy that involves two aspects: (1) formulation of the equations following SAM and (2) using the automatic differentiation (AD) technique to compute the Jacobian matrix necessary to solve the equations. Finally, an illustrative example is presented to demonstrate the feasibility of this approach and how its results compare to those of a traditional simulation method. [ABSTRACT FROM AUTHOR]

Improved IT technology makes possible real-time evaluation of energy use on the scale of an electric distribution network using common utility bills or interval data as a data source. However, the available data are faulty and require validation and estimation. Because of the large number (typically millions) of meters to be monitored on a daily basis for years, visual inspection and other techniques that rely on human intervention are not suitable. This paper discusses simple, automatable methods and algorithms to validate and estimate monthly utility bills, which continue to be the most ubiquitous form of energy use measurement. A new method to identify suspect or missing bills is presented, as well as a choice of methods for replacing the suspect or missing bill with the most likely estimate. [ABSTRACT FROM AUTHOR]

In line with the mission of the National Park Service, the Zion National Park Visitor Center was designed to use 70% less energy than a comparable visitor center built to Federal Energy Code 10 CFR 435 (DOE 1995). The authors and NPS staff used an integrated design process, including extensive simulations, to minimize the energy consumption. The result was a passive solar commercial building that has a good thermal envelope, daylighting, and natural ventilation. Passive downdraft cooltowers provide all the cooling. Two Trombe walls provide a significant amount of the heating. After two years of metering, the results show a net energy use intensity of 24.7 kBtu/ft² (280.5 MJ/m²) and a 67% energy cost saving. Low energy use and aggressive demand management result in an energy cost intensity of $0.43/ft² ($4.63/m²). The paper discusses lessons learned related to the design process, daylighting, PV system, and HVAC system. [ABSTRACT FROM AUTHOR]