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The purpose of this paper is to present a methodology for the design and predictive control of thermal zones with bifacial semi-transparent photovoltaic (STPV) windows, motorized venetian blinds (MVB), and hydronic radiant floor heating (HRFH). Solar gains and daylight are controlled by the blind tilt angle, β, of the motorized venetian blinds, for passive heating and natural daylighting in the zone. Near-optimal temperature setpoint strategies control the room temperature with hydronic radiant floor heating, which promotes preheating overnight, before the morning peak demand period of the grid in Quebec (6-9 AM), and in the afternoon, before the evening peak period of 4-8 PM. We can increase the energy flexibility in the building electricity demand profile with a predictive control model of window and blind transmittance and zone setpoint profile, based on a one-day ahead prediction for different design days in the heating season. An explicit finite difference thermal network model is used to predict heating loads and the building temperature profile associated with the thermal response of the zone. The energy flexibility in the demand profile is quantified by a building energy flexibility index (BEFI) [2]. The concrete slab thickness of the hydronic heating system will be analyzed parametrically to further improve the energy flexibility and efficiency of the thermal zone. Four different slab thicknesses of concrete are considered, including 5, 8, 10, and 12 cm (1.97, 3.15, 3.94, 4.72 in), while three different window-to-wall ratios (%) are considered. A 10 cm (3.94 in) thick slab and 32% WWR produces a BEFI = 100% for both morning and peak periods, for a cold and clear February day, in Montreal; completely displacing the heating demand for the peak periods. There are several pre-determined design variables for this zone, including the building orientation and the coverage ratio of the STPV (%). Simulations are based on a typical zone at a test facility on Concordia's Loyola campus, which will be validated experimentally in the future. [ABSTRACT FROM AUTHOR]

The energy use for indoor and greenhouse horticulture has grown dramatically over the past 15 years, driven both by the legalization of medical and recreational marijuana and the increasing interest in sourcing ingredients from local farms year-round. Nationally, indoor horticulture facilities were estimated to consume 20 billion kWh of electricity in 2012 corresponding to 1% of electricity use nationally (Mills, 2012). Since 2012 nearly 18 states have legalized recreational marijuana and many more have seen growth in the local food movement, only increasing demand from these facilities. Because of the desire to recreate optimal outdoor growing conditions, indoor horticulture facilities typically have energy use intensities (EUIs) that are twice that of fast-food restaurants and can exceed even data centers. The lighting power density (LPD) in the facilities can be 80 times that of the lighting power density in office buildings and the lights operate on average 18 hours per day. Thus, most of the energy used in these facilities is for lighting and HVAC and dehumidification systems to maintain ideal temperature and humidity levels. In 2017, the American Society of Agricultural and Biological Engineers (ASABE) released ANSI/ASABE Standard S640 which established a metric, µmol/J (micromoles per Joule), to measure the photonic efficacy of lighting used in horticultural applications. In 2018 the Design Lights Consortium (DLC) began establishing criteria for LED luminaires for these applications. In due time, the 2021 International Energy Conservation Code (IECC), Title 24-2022, and many other standards, including ASHRAE 90.1, have adopted or are considering lighting photonic efficacy limits in indoor horticulture facilities, driving significant energy savings. Utilities also have begun to offer incentives to reduce energy use in these facilities using DLC's LED photonic efficacy threshold of 1.9 µmol/J. The 2021 IECC also for the first-time established insulation criteria for the envelope of heated greenhouses. This paper describes the technical and policy considerations used at the national, state, and local levels to reduce energy use from these facilities and the potential for an addendum to ASHRAE 90.1 on new lighting efficacy requirements. The authors also provide recommendations for future steps in standards to reduce the energy use of HVAC and lighting loads in both indoor horticulture facilities and greenhouses. [ABSTRACT FROM AUTHOR]

The Kingdoms’ electricity consumption has been steadily increasing during the past 10 years, with the residential sector consuming nearly 45% of it. Therefore, the residential sector offers a real opportunity for energy savings, as one of the reasons for this high-energy consumption is the utilization of low efficiency electric home appliances, e.g., electric water heaters (EWH). This behavior is encouraged due to the low initial investment for inefficient appliances, compared to the more efficient ones. Electric Heat Pump Water Heater (EHPWH) can substantially reduce water-heating-related energy use in the Saudi residential sector. This paper investigates the potential savings in primary energy, and its corresponding carbon dioxide (CO2) reduction, achieved by switching from conventional low efficiency electric resistance water heaters to EHPWH. The potential energy savings is nearly 0.19 Quadrillion Btu (0.20 Exajoules), and a corresponding 28,660 million pounds (13 million metric tons) of CO2 emissions reduction. This study paves the road for policy makers to take a deep dive investigation of this proposal. [ABSTRACT FROM AUTHOR]

The decarbonisation of the UK economy, driven by the national net-zero target, will require the large-scale electrification of important fields within the energy sector, such as transport and heating. The increase in electricity demand associated with this process will mean that flexible and integrated energy systems will be increasingly relevant in the future, especially in terms of improving the efficiency of energy use and alleviating stress on the electricity grid. District heating is a key technology in this process, particularly in densely populated urban centres, as it enables the integration of heating with other energy vectors and unlocks the potential for urban waste heat recovery to deliver significant carbon and cost savings. This paper aims to investigate how the benefits of a waste heat recovery system can be maximised through its flexible operation. This will be achieved by modelling the coupling of thermal energy storage (TES) with a district-scale heat pump, based upon time-of-use electricity prices and the concept of an existing system that recovers waste heat from the London Underground mass rapid transit system. The results from this investigation are reported together with recommendations for further development and future deployment of heat recovery from subway systems in general. [ABSTRACT FROM AUTHOR]

Buildings consume approximately 40% of total energy consumption in the U.S., thus there is significant motivation to make buildings more efficient. Existing studies have implemented a range of control strategies to save energy in typical commercial buildings. However, academic buildings at universities can vary substantially from typical office buildings in their space use, occupancy patterns and energy use. This paper aims to evaluate the energy savings potential of implementing occupant-based control (OBC) for HVAC systems in typical academic buildings using the energy simulation engine EnergyPlus. A U.S. DOE Commercial Building Prototype Model was modified to represent the typical characteristics and space use compositions of academic buildings based on the space type and functional use data collected from 8 U.S. universities. The occupancy schedules were then replaced with stochastic academic building-based occupancy schedules, developed from a prior study by the authors. Next, the baseline and proposed models were built, of which a fixed setpoint schedule and minimum outdoor air flowrate were used for the baseline model. The proposed model resets the temperature schedule and minimum outdoor air flow schedule based on the proposed occupancy schedules, following the recommendations of ASHRAE Standard 90.1-2019, and ASHARE 62.1-2019. The results of this work provide typical academic building models with integrated occupancy schedules which can be used to evaluate energy saving measures, and aid building designers and operators in making informed decisions in applying appropriate control strategies to optimize building energy systems, as well as predict energy use and demand. [ABSTRACT FROM AUTHOR]

The energy supply in Austria was first established in the 1880s with regenerative microgrids for industries and public buildings. These were unified and modernized step by step to form what is now one of the most reliable power supply systems in the world. A large share of more than half of the power production comes from hydro power stations, many of which also provide pump storage. Since the 1950s, previously wasted heat from fired power stations has been distributed to dense urban areas via district heating. Oil price crises, rising awareness for environmental issues, and increasing availability of incinerable waste have led to a diversification of fuel and inclusion of geothermal heat and waste heat from industrial processes. Public buildings and communities were at the start of the Austrian modern energy supply system, and with growing demand for transformation of energy supply to meet net zero requirements, today they serve as models for the future. Thus, the efforts and methodology applied on Austrian university campuses are presented here as a result of the Austrian Research Promotion Agency (FFG) Project 864147, funded by the Austrian Federal Ministry for Climate Action, Environment, Energy, Mobility, Innovation and Technology, to contribute to the International Energy Agency Energy in Buildings and Communities Programme (IEA EBC) Annex 73, Towards Net Zero Energy Public Communities, which focuses on developing guidelines and tools that support the planning of net zero energy resilient public communities. Two case studies illustrate the transition towards net zero resilient energy: • Case Study 1: The Campus Technik of University of Innsbruck, where building envelopes and building technology have been modernized to reach an energy consumption close to what is achieved in high-quality new construction, with inclusion of heat regeneration from ventilation and use of ambient cold for night ventilation. • Case Study 2: The new campus of Wirtschaftsuniversität (WU) Wien, which uses groundwater heat in a cyclic way both for heating and cooling, where core activation allows for mostly direct use without the need for heat pumps to adapt temperature levels. This paper briefly describes the specific Austrian situation of legislation, tradition, and policy that creates the framework for changes towards net zero energy supply. The two case studies illustrate how this framework has been handled by the planning teams to meet the objectives in the most cost-effective way and how challenges have been dealt with and successfully overcome. [ABSTRACT FROM AUTHOR]

In most climates heating and cooling systems place large demands on the electrical power grid. This paper will discuss the concept of 'Energy Farming' harvesting and storing as a method of reducing these demands and their impact on the global climate. Whilst 'Energy Farming 'is of interest as a means to reduce the required capacity from the electrical infrastructure, the discussion will extend to reducing the total installed cooling capacity and energy demand. The paper will explore the relationship between mechanical cooling and electrical demand profiles and consider the benefits of storing energy. This will include traditional methods of thermal storage such as ice storage with unconventional operational regimes. The use of 'Energy Farming 'is of particular importance in countries with expanding populations, increased energy demand and consumption. The discussion will further extend to the increased use of renewable technologies such as wind power and solar power. A climate friendly building 'Farms Energy'. [ABSTRACT FROM AUTHOR]

Today's modern enterprise data center must be capable of efficiently operating at current average power densities of 30 to 50 W/ft² (∼320 to 540 W/m²) and, based upon industry trends, support growth in the foreseeable future toward 150 W/ft² (∼1,610 W/m²) and also incorporate provision to possibly support significantly higher power densities in local areas. This paper summarizes the industry trends toward greater power consumption and higher processing speed servers and gives an overview of current and expected techniques for cooling high power consuming cabinets and mainframes. The potential impact of these trends and new techniques on the design of the raised floor cooling system will also be discussed. Additionally, during the installation of new equipment and the migration of equipment from other data centers to the new center, the new data center at start-up is often required to operate with almost no computing equipment load. The start-up conditions can be an operational problem for equipment sized to operate at maximum load. In response to the potentially large range of power density operation and the high costs of data center construction, the majority of owner/operators plan to accommodate this expected power density growth in phases. This paper summarizes the planning to accommodate the various load conditions of the mechanical systems for one recently designed data center including raised floor cooling, central plants, and pipe distribution. [ABSTRACT FROM AUTHOR]

This paper discusses a technical comparison of a direct-expansion ground-source heat pump (DX-GSHP) and an air-source heat pump( ASHP). To lower the ground heat exchanger size for cost reduction purposes, the system performance of a hybrid system is also evaluated using a supplementary air evaporator combined with the DX-GSHP. Detailed screening models previously developed for ASHPs and DX-GHSPs are first used to compare the seasonal performance of these two options for a residential building in the cold-climate city of Montréal, Canada. Then, the model is adopted for performance evaluation of the hybrid system. Additionally, different parameters including borehole total length and heat pump capacity are varied to evaluate their impact on the seasonal system performance. The results show that by adequate sizing, total and peak electricity consumption of the DX-GSHP system can be reduced by 50% and 40%, respectively, compared to an undersized DX-GSHP system. However, system energy savings from using a hybrid ground-source heat pump (HGSHP) are marginal compared to a DX-GSHP (5.5% for a low-capacity system), and these savings are happening during the shoulder months. Such results highlight the importance of further investigations in the area of DX-GSHPs to reduce the borehole installation cost and increase its performance. [ABSTRACT FROM AUTHOR]

According to some estimates, pumps account for between 10% and 20% of world electricity consumption (EERE 2001; Grundfos 2011). Unfortunately, about two-thirds of all pumps use up to 60% too much energy (Grundfos 2011), primarily because of inefficient flow control. Varying pump speed using a variable-frequency drive (VFD) on the pump motor is one of the most efficient methods of flow control. As a consequence, about one-fifth of all U.S. utilities incentivize VFDs (NCSU 2014), and many of these drives control pumping systems. However, field studies and research show that few variable-flow systems are optimally controlled, and the fraction of actual to ideal savings is frequently as low as 40% (Kissock 2012;Maet al.2015; L. Song, Assistant Professor, Department of Mechanical Engineering, University of Oklahoma, pers. comm., July, 2013). Utility incentive programs that rely on ideal energy saving calculations could overestimate savingsby 30% (Maxwell 2005). Previous work has shown the importance of changing motor efficiency, VFD efficiency, and pump efficiency on savings (Bernier and Bourret 1999; Maxwell 2005). This work considers the difference between actual and ideal savings caused by excess by pass flow, positions and setpoints of control sensors, and control algorithms. This paper examines the influence of these factors on energy savings using simulations, experimental data, and field measurements. In general, energy savings are increased when bypass is minimized or eliminated, pressure sensors for control are located near the most remote end use, and the pressure control setpoint is minimized. [ABSTRACT FROM AUTHOR]

Semi-empirical models were developed for fan airflow output, fan power consumption, and primary airflow for series fan-powered variable-air-volume terminal units with electronically commutated motors. Eight series terminal units with either 8 in. (203 mm) or 12 in. (304 mm) primary inlets from three terminal unit manufacturers and two motor manufacturers were evaluated. Fan power and airflow data were collected at a downstream static pressure of 0.25 in. w.g. (62.3 Pa). Upstream static (primary air) pressures were varied from 0.0 to 2.0 in. w.g. (0 to 498 Pa). Data were collected at four primary inlet damper positions and at four fan motor settings. Model variables included primary air inlet damper position, fan motor input setting, the air inlet differential sensor pressure, and the upstream (primary air) and downstream (supply air) static pressures. All of the resulting fan power and airflow models had R2 values greater than 0.895. The models for the fan airflow output and fan power had R2 values greater than 0.968. The models developed in this paper can be used in HVAC simulation programs to estimate the energy use and potential savings of series fan-powered terminal units with electronically commutated motors. [ABSTRACT FROM AUTHOR]

Calibrated energy models are useful for commissioning building systems, measurement and verification (M&V) of building retrofit projects, and predictions of savings from energy conservation measures. This paper presents the modeling and calibration process for building energy models of a DoD (Department of Defense) building. The models are developed using EnergyPlus and TRNSYS simulation programs with measured data from an enhanced building management system (BMS) which includes an on-site weather station. The building under study is the Atlantic Fleet Drill Hall located at Naval Station Great Lakes, IL. This LEED® Gold certified building with a total floor area of 69,218 ft² (6,431 m²) consists of a drill deck and administrative offices. Static data from as-built drawings and dynamic data from building operations are collected and analyzed to create energy models with EnergyPlus and TRNSYS. An extensive sensitivity study by systematically perturbing more than a thousand model input parameters is employed for model calibration. Those parameters that most affect the building energy end-use are selected and refined to calibrate the models. The calibration results, as well as problems encountered throughout the process from the user's perspective, are discussed. The total facility and individual equipment electricity consumption predictions from the calibrated models closely match the measured data. [ABSTRACT FROM AUTHOR]

Our paper presents findings from in-depth monitoring of two single-family "Net Zero Energy Homes" (NZEH) in Massachusetts, begun in July and October 2010 respectively. It concentrates on the cooling period 2010. In both buildings, we measured the electric energy consumption at the circuit level. In addition, we measured parameters related to indoor comfort and indoor air quality on seasonal test series. Based on these measurements, we generated average daily electric load profiles during a large portion of the cooling season. We also used indoor temperature and relative humidity measurement to evaluate thermal comfort based on static and an adaptive comfort models. Finally, we used CO2 concentration measurements as an indicator for indoor air quality (IAQ) and to assess the sufficiency of air exchange rates. [ABSTRACT FROM AUTHOR]

This paper summarizes the results of field testing to evaluate the performance of simplified and optimal control strategies for shifting peak cooling loads and reducing building energy costs through the utilization of both the passive and active thermal energy storage systems for an elementary school in Colorado. In particular, the performance of precooling of building thermal mass as well as real-time model-based predictive optimal controls is evaluated. The results indicate that the school is saving roughly 47% on its annual electricity costs by utilizing the TES operated using their optimal control strategy. [ABSTRACT FROM AUTHOR]

An independent dehumidification air-conditioning system has been built in Beijing, China. The dehumidificaiton is done by a hot water-driven liquid desiccant dehumidification subsystem. This paper reports results of field measurement of the system, which shows that the system can produce a comfortable indoor environment even in very humid weather. On dry days, the dehumidification system bears around 40% of the total load, while on humid days, it bears around 50%. Economic comparison of the independent dehumidification system and a conventional system indicates that the two systems have equivalent distribution power consumption, but the former one may save about 30% cooling source cost when the price ratio of electricity to heat is reasonably set. [ABSTRACT FROM AUTHOR]

Hydronic distribution systems account for approximately 20% of the world's energy use per a study by US DOE and the Hydraulic Institute. Many existing pumps and motors are oversized in capacity by more than 20%, applied with a 100% capacity redundancy in the form of an extra pump, and operated at a constant speed throughout the heating season. Triple duty and balance valves are often implemented in design to throttle the pump flow to match design. Due to equipment oversizing, the actual operating point often does not position well with the pump's best efficiency point. This leads to decreased pump efficiencies, higher motor electricity consumption, and increased maintenance and operational costs due to excessive wear of system components. Over pumping reduces boiler loop differential temperature resulting in more frequent boiler cycling, inefficiencies, and increased gas use. GTI Energy performed demonstrations of emerging space heating hot water distribution system improvements to generate electricity savings while minimizing capital investments and maintaining resiliency at two (2) Illinois Army National Guard (ILANG) Facilities. This demonstration sought to generate electricity savings by optimizing the pump selection process through a "right-sizing" approach, while also improving system operation through variable flow conversion and parallel pump controls. Application economics, lessons learned, installation best practices and commissioning processes to ensure success are also presented. Site A involved retrofitting an existing pump with a Variable Frequency Drive (VFD) to develop a system performance curve. A right-sized pump was then selected to provide the constant system flow rate of 250 gpm (15.8 lps) and achieved a significant reduction in power draw from 11.06 hp (8.25 kW) to 2.9 hp (2.16 kW) and reduced electric consumption of 74%. Site B's oversized building loops pumps operated at constant speed with 100% capacity redundancy. These pumps were replaced with right-sized pumps, with on-board Sensorless Electronically Commutated Motor (ECM) Controls and operated in parallel to serve the building zones. The secondary loop flowrate was commissioned by ensuring the flowrate at the extreme end-of-the-loop coil matched the coil specifications during design day conditions. This demonstration at Site B decreased electric demand from 1.38 hp (1.03 kW) to below 0.67 hp (0.5 kW) and reduced electric consumption by 46%. [ABSTRACT FROM AUTHOR]

Over the last decade, the global fight against climate change through electrification has led to an increase in research on building heating, ventilation, and air conditioning (HVAC) systems that utilize intelligent control algorithms to provide demand-side grid service while maintaining the thermal comfort of building occupants. As the pivotal point between building electricity consumption and indoor thermal comfort, high-efficiency electrical heat pumps are at the center of these emerging studies, and various grid-interactive and occupant-comfort control algorithms have been developed for them. The impact of these algorithms on the heat pump operation and performance under different weather, building load, and grid requests calls for investigation and verification via experimental tests with actual heat pumps integrated with real-time building and grid responses. This study presents a Water-Source Heat Pump Hardware-in-The-Loop (HIL) Test Facility developed with the capability to perform such tests. The hardware configuration for this test facility introduces a hydronic system that emulates the conditions for the heat pump water-side, and a duct system that emulates conditions for the heat pump airside. Both data acquisition and emulator control are implemented through the National Instruments (NI) LabVIEW software running on an NI PXI platform. The HIL mechanism based on the hardware-software integration that allows the testbed to communicate with a generic simulation environment is also discussed. Currently, the test facility setup includes a single heat pump and virtual building model in EnergyPlus coupled with an occupant behavioral model in MATLAB. Preliminary test results of the current setup demonstrate the building load emulator's ability to track the simulated zone temperature with a Root Mean Square Deviation (RSME) below 0.12°C (0.216°F). An uncertainty analysis based on sensor accuracies shows that the heat pump coefficient of performance (COP) can be measured with a relative uncertainty of 10.4% in cooling and 3.7% in heating. Apart from the current testing on a single heat pump, the test facility also provides the flexibility to include additional heat pumps to form a heat pump cluster, as well as coupling the heat pump with active thermal storage to provide enhanced demand flexibility. [ABSTRACT FROM AUTHOR]

Following a major outbreak of the COVID-19 pandemic and strong rise in cases, the daily life of people in the United States was significantly impacted. The pandemic resulted in 'stay-in-home' orders for many people, which generally required people to stay in their residences except for necessities, for several months during mid-2020 and beyond. As many people started working from home, it resulted in a change in their typical activities and daily routines, and therefore for many, it also had as significant impact on their home's energy consumption. However, given the limited submetered energy consumption data available for the large majority of homes, there are not many studies that analyze the impact of the pandemic on energy consumption at the household-level. In this study, the electricity used by energy consuming building systems (non-HVAC only), for multiple homes is compared during the pandemic (2020) and pre-pandemic (2018) time in a hot and humid climate in Austin, Texas. A high resolution and disaggregated energy consumption dataset were used for a total of 42 housing units. Electricity consumption data was compared at different time intervals to determine which energy consuming devices change in use most during 2020. Overall electricity use increased significantly for many of the housing units studied during normal business hours on weekdays. Depending on the time of day, the specific appliances and end uses increased in electricity use most. As the peak of the pandemic subsides, it is likely that some of the changes in behavior and work-from-home scenarios will be different than pre-pandemic times, likely having long-timer impacts on energy consumption behavior and energy use in residential buildings. This is important for improving the accuracy of building energy modeling and grid-level energy demand predictions. [ABSTRACT FROM AUTHOR]

Buildings in the U.S. are responsible for approximately 40% of energy and 70% of the electricity consumption. To address rising greenhouse gas emissions and climate changes, various studies have explored strategies to reduce energy consumption in buildings. One opportunity to improve the building envelope performance is through improvements to fenestrations, particularly complex multi-layer fenestration systems for exterior windows. Windows are the least thermally efficient of all components in a typical building envelope. Windows also permit solar radiation into a building, which significantly increases the building energy consumption during the summer season. Meanwhile, windows are necessary to provide occupants with natural light, a view to the outside, and to support productivity. Thus, there is a need to strike a balance between energy savings, and the thermal and visual comfort impacted by windows. Traditionally, shading devices are one method used to adjust the amount of heat and light entering an interior space. However, such shading devices are typically operated manually by occupants, and are seldom used effectively over time. Currently the building energy simulation program EnergyPlus, has limited capabilities to model shading devices, and more limited abilities to model dynamic fenestrations. In this study, thus, we propose to model and validate several types of automated multi-layer fenestration elements, using co-simulation of EnergyPlus and Radiance using laboratorycollected data. EnergyPlus was used to model energy consumption and thermal comfort while Radiance was used to model lighting levels. BCVTB was used to interface between EnergyPlus and Radiance to facilitate co-simulation. To validate the models, experimental data was collected from 5 illuminance sensors in an exterior office space located in a test facility in Ankeny, IA. This model methodology can be used to improve the flexibility and modeling capabilities of dynamic fenestration elements for building energy performance evaluation methods. [ABSTRACT FROM AUTHOR]

Measurement of the heat loss from equipment in buildings is necessary in order to make accurate assessments of its impact on cooling loads. Advances in the design of buildings and improvement of the thermal characteristics of insulation materials and building envelope systems have significantly reduced the cooling load from external sources; however, the addition of various types of office equipment to buildings has become a major source of internal cooling load. Some equipment includes a nameplate rating showing total power consumption, while other equipment does not. Some manufacturers measure the equipment's maximum electric power consumption and list that as a power rating on the nameplate or in the equipment literature, while others list the equipment's maximum power capacity. Since the manufacturers' power ratings, if reported, are usually based on instantaneous measurement while the equipment is working at maximum capacity, use of equipment nameplate values for cooling load calculations may lead to oversizing of air-conditioning equipment, resulting in an extra initial cost as well as higher operating costs. On the other hand, underestimating the cooling load may result in insufficient cooling capacity. Another factor affecting calculation of cooling load is the split between the radiant and convective heat loads from the equipment. The convection portion of the heat transferred from the equipment to the surroundings is an instantaneous load, since it is added to room air by natural or forced convection without time delay, whereas the radiation portion is absorbed by the surfaces of the room and then dissipated over time. Accurate determination of cooling load is important in gauging the proper size of air-conditioning equipment. This article presents experimental results for the total heat gain and radiant/convective split from a sampling of the different types of equipment used in offices. The nameplate vs. measured values, operational vs. idle values, and radiant vs. convective values are compared and discussed. [ABSTRACT FROM AUTHOR]

The building sector is one of the most significant contributors to energy consumption, and it accounts for approximately 40% of the total energy consumption globally. Therefore, energy-efficient buildings received a lot of attention to reduce energy consumption and greenhouse gas emissions. Previous studies showed that the integration of the Thermal Energy Storage (TES) system in buildings has great potential in reducing heating and cooling energy demand while maintaining occupants' thermal comfort. In the last couple of decades, Phase Change Materials (PCM) have received considerable attention as a Latent Heat TES system for passive heating and cooling applications in buildings. PCM can be used as building envelope material, and it can store or release heat during the phase change process. Previous researchers used PCM as a retrofitting option to enhance occupants' thermal comfort in residential buildings. The results showed that using PCM could be a great approach to saving energy. Most of the previous studies were conducted experimentally, and only a few studies tried this with building energy simulation. Therefore, in this study, we use the building energy simulation software (EnergyPlus) to investigate the effect of different types of PCMs on the energy efficiency of a typical small office building in different climate conditions. Results show that, depending on the climate zones, the performance of using the PCM is different. Also, the building energy results varied with the type of the PCMs and the thickness of the PCMs. [ABSTRACT FROM AUTHOR]

Smart control system technologies for combined heat and power (CHP) units are not previously reported in literature, and have potential to generate significant savings. Only minimal capital investment is required in infrastructure and software development. A live cloud-based solution has therefore been developed, and installed in a real UK supermarket store, to optimise CHP output based upon predicted price forecasts, and live electricity and head demand data. This has allowed validation of the optimiser price forecasts, and predicted cost savings, and a model of the optimiser has therefore been applied to three case study sites. The model itself has also been validated against the installed optimiser data. The pre-feasibility analysis undertaken indicates cost savings between 2% and 12%. CHP units sized within the feasible operating range, above a part load level of 0.65, generate the greatest percentage savings. This is because the optimiser has the greatest flexibility to control the CHP output. However, larger units, even though less nearly optimal, may actually generate greater overall savings and would therefore be targeted for earlier optimiser implementation. Installation costs are not expected to vary greatly from site-tosite. Some stores, though, show no material improvement over the existing control systems, demonstrating the value of the pre-feasibility analysis using the model. Though waste heat increases significantly with all strategies, the propensity to sell this heat within the UK is likely to improvein the near future. [ABSTRACT FROM AUTHOR]

Semi-Transparent Photovoltaics (STPV) can be integrated on Double Skin Facades (DSF) to enhance the electrical and thermal performance of a building. In a mechanically ventilated DSF, the heat extracted from the DSF can be used to increase the Coefficient of Performance (COP) of a heat pump based mechanical system, or it can be introduced directly to the building. In addition, the STPV integrated on the outermost layer of the DSF, can control the solar gains, may allow controlled levels of the daylight into the zone and creates a microclimate around the building. In the present study we investigate the mismatch between the electricity production by the STPV and the electricity needed for heating and lighting by the adjacent building zones and develop ways of reducing this mismatch. A DSF-STPV combination, coupled with battery storage within the building, is considered in order to shift the peak demand of the building and provide better matching of generation and loads. Because STPV is integrated in the DSF, the heating demand during the day decreases as the building receives solar heat gains and at the same time produces electricity. This electricity produced by the STPV can be stored in a battery and later be used at the grid peak hours to reduce the peak demand by operating the heat pump. The preheated air, that is flowing within the cavity of the DSF-STPV, assists an air sourced heat pump to increase its COP and the heat produced is used to keep the building warm during the grid peak hours when the set point is reduced. With the use of such a predictive heating strategy, the peak demand of the building can coincide with the peak of the solar electricity production resulting in more than 80% reduction in the electricity consumption during the peak demand hours of the grid. [ABSTRACT FROM AUTHOR]

In the United States, approximately 40% of the primary energy use and 72% of the electricity use belong to the building sector. This shows the significance of studying the potential for reducing the building energy consumption and buildings’ sustainability for ensuring a sustainable development. Therefore, many different efforts focus on reducing the energy consumption of residential buildings. Data-validated building energy modeling methods are among the studies for such an effort, particularly, by enabling the identification of the potential savings associated with different potential retrofit strategies. However, there are many uncertainties that can impact the accuracy of such energy model results, one of which is the weather input data. In this study, to investigate the impact of spatial temperature variation on building energy consumption, six weather stations in an urban area with various urban density were selected. A validated energy model was developed using energy audit data and high-frequency electricity consumption of a residential building in Austin, TX. The energy consumption of the modeled building was compared using the selected six weather datasets. The results show that energy use of a building in an urban area can be impacted by up to 12% due to differences in urban density. This indicates the importance of weather data in predicting energy consumption of the building. The methodology and results of this study can be used by planners and decision makers to reduce uncertainties in estimating the building energy use in urban scale. [ABSTRACT FROM AUTHOR]

There is a need to decrease the peak electricity demand by reducing the energy used in space conditioning in order to reduce the stress on the electricity grid. Thermal energy storage (TES) has the potential shift the peak electricity demand. PCM is a type of TES that is researched to be included in the building envelope. This study introduces a new full size environmental chamber capable of testing full scale envelope panels and develop experimental data to validate PCM models used in building energy simulation programs. [ABSTRACT FROM AUTHOR]

Urbanization is driving rapid growth of mechanical cooling around the world, much of it in hot climates. Adoption of minimum energy performance standards can significantly reduce global growth of electricity demand associated with cooling. Performance standards aim to minimize equipment life-cycle cost by setting performance levels appropriate for a given climate. A typical UAE 8760-hour cooling load profile is developed. A component-based chiller model is validated by monitored data from a baseline chiller that meets the highest MEPS currently in effect of SCOP=3.5 W/W. Performance maps are produced for a series of progressively higher performance chiller designs and LCC analysis is carried out using component costs and annual simulation results until the least life-cycle-cost design is found. A high performance air-cooled chiller minimum performance level of SCOP>5.0 W/W is life-cycle cost-effective in UAE's hot climate. [ABSTRACT FROM AUTHOR]

Compared with other types of buildings, high-rise buildings have a higher cooling load and are more energy-intensive, which leads to periods of peak electricity demand on the utility grid during the summer. Therefore, reducing the cooling load of high-rise buildings is critical to energy savings and reduction of peak electricity demand. Ventilative cooling (VC) has proved to be an effective solution to reduce cooling load. However, the stack effect in the large vertical spaces of high-rise buildings, e.g. atria, is beneficial for VC but is also a great challenge for high-rise fire smoke protection. Segmentations were often applied in the large vertical space of high-rise buildings to reduce the stack effect for fire smoke protection. The authors’ previous study found that the segmentation could effectively protect the upper space which is far from the fire source, but it reduces the energy savings of VC due to the higher flow resistance. In this study, a novel ventilation approach using an independent shaft in atria for achieving fire safety and energy efficiency was proposed. The shaft is designed for VC when there is no fire and exhaust smoke when fires happen. CFD simulations and building energy simulations were used to study its VC and fire protection performance. The results indicate that the independent shaft could effectively remove indoor overheating and exhaust smoke. [ABSTRACT FROM AUTHOR]

The impact of the high power requirements of large residential tankless electric resistance water heaters on electric system distribution wiring, transformers, breakers, and other equipment is of concern for both electric utilities and builders. This study was undertaken to analyzehowprobable and worstcase diversified electrical demand of large (28 kW) residential tankless electric water heaters compares to that of 4.5kWstorage (tank-type) water heaters in residential applications as a function of the number of households on a given electrical distribution circuit. This work developed methods to estimate both most likely (most statistically probable) and 3-sigma (statistically improbable but theoretically possible) worst-case diversified electrical demand for both tankless and tank-type water heaters as a function of the number of households. As expected, single households experience peak water heating electrical demands that correspond to the maximum power rating of the water heaters. However, time diversity of hot-water use increases rapidly as more households are added, resulting in diversified electrical demand of large tankless electric water heaters dropping rapidly from maximum values as the number of households on an electrical distribution system increases. Probable tankless water heater diversified electrical demand drops to levels only slightly higher than for tank-type units when even only a few (2 to 10) households are on a given distribution system, and it continues to drop even further as more households are added. Importantly, this work computes diversified electrical demand estimates using three totally different methods, showing that there are multiple analysis techniques that all lead to the same conclusions--namely that diversified electrical demand of 28 kW tankless electric water heaters rapidly drops to levels near to that of 4.5 kW storage electric water heaters when even only small numbers of households are considered. [ABSTRACT FROM AUTHOR]

Modeling and simulation of energy consumption in 86% of the Ryerson University (RU) campus buildings is presented. Energy simulation models were developed for 16 major Ryerson University buildings. Commercially available software was used for the prediction of energy use. All of the possible sources and uses of energy in the buildings were accounted for in the modeling and simulation. Simulation result showed that 26% of total energy was used by lighting, 19% of total energy used by plug load, and 4%> of total energy was used by miscellaneous equipment. The remaining 51% of energy use was for heating, ventilation and air-conditioning (HVAC) systems. In addition, the Princeton scorekeeping method (PRISM), a widely used method in energy conservation studies, has been used to analyze the same RU buildings for comparison and verification. The base case simulation residt and the Princeton scorekeeping method result were compared with the Campus Planning actual use bills for electricity, steam and deep lake water cooling (DLWC) demand for the Ryerson campus. The simulation residt underpredicted electricity use by 5.7%> and steam consumption by 6.3%, while the Princeton scorekeeping method underpredicted electricity use by 2.7%, and overpredicted steam consumption by 6%. The average energy intensity was determined as 1.04 GJ/m² (91,576 Btu/ft²) for the 86% of the total area of Ryerson campus. Sensitivity analysis was conducted by (1) adding a heat recovery system and (2) reducing lighting schedule. As a result, theformer analysis predicted an annual energy saving of 5,6%>for cooling load and 76% for the heating load, while the latter analysis predicted an annual energy savings of 10% for cooling load and 21%for electricity demand, while the heating load increased by 14%. [ABSTRACT FROM AUTHOR]

This is an analysis of electrical and water consumption for cooling systems involving refrigeration with dry coolers, water economizers and air economizers combined with steam, ultrasonic and evaporative humidifiers on telco/data centers located at various cities throughout the United States. Air economizers with evaporative humidifiers are the most energy efficient model, although the savings are quite small for tropical locations. Air economizers are often able to satisfy cooling requirements without any refrigeration and are also able to reduce refrigeration load for additional time. These periods when refrigeration is not required have improved reliability uptime and provide low risk opportunities for chiller plant servicing. The Air economizer system also consumes less water than water economizer or refrigeration only systems. Water economizers are less effective than air economizers at improving energy efficiency and reducing refrigeration dependency. The modeled dry cooler did not provide any savings versus refrigeration only. Evaporative humidifiers are more efficient than ultrasonic humidifiers and much more efficient than steam humidifiers. Air economizers with steam humidifiers are an energy wasteful design. More power is consumed by the steam humidifiers than is saved by the air economizers. [ABSTRACT FROM AUTHOR]

The US Department of Energy's Building America residential systems research project uses an analysis-based systems research approach to identify research priorities, identify technology gaps and opportunities, establish a consistent basis to track research progress, and identify system solutions that are most likely to succeed as the initial targets for residential system research projects. This report describes the analytical approach used by the program to determine the most cost-effective pathways to achieve whole-house energy saving goals. This report also provides an overview of design/technology strategies leading to net zero energy buildings as the basis for analysis of future residential system performance. [ABSTRACT FROM AUTHOR]

A 10-year-old thermal energy storage (TES) installation continues to perform efficiently and economically at the heart of a district energy (DE)/combined heat and power (CHP) system in Chicago, Illinois. The thermal end-users include a major conference/exposition facility, a high-rise luxury hotel, and nearby public and private building facilities. The TES system is one of the largest in the world with a TES capacity of 123,000 ton-hours and a peak design discharge rate of 25,000 tons. The system employs a single welded-steel, aboveground storage tank with stratified low-temperature fluid as the storage medium. The TES system has exhibited the flexibility to continually evolve over time with the growing DE system. Initially, the TES system operated at conventional supply and return temperatures, in conjunction with existing CFC-based centrifugal chillers. As the DE system grew, the TES system was operated at an expanded ΔT of 24°F (13.3°C) (30°F [-1.1°C] supply and 54°F [12.2°C] return) in conjunction with ammonia-based screw chillers and single-stage steam absorption chillers. The various system customers accept supply temperatures to suit their specific needs, from 30°F–34°F (-1.1°C–1.1°C) for use with low-temperature air distribution systems to 42°F (5.6°C) for conventional existing systems. Peak contract cooling load has already grown in several phases, from 8,000 tons in 1994 to well over 20,000 tons in 2000, with the potential for much higher load in the future. Initially operating in a full shift mode, as the DE system expands, the TES can be employed in a partial shift mode on peak days while remaining in a full shift mode during low-load days. The TES system has accommodated various electric utility rate structures and enabled the economic deployment of cogeneration. The TES system had very low initial capital cost and has provided dramatic reductions in operating energy costs. The TES system was initially specified and designed for an operating life of at least 29 years without any scheduled maintenance requiring draining of the tank. To date, the TES system has required near-zero maintenance. Meanwhile, the use of the low-temperature fluid has eliminated the need for conventional ongoing water treatment for corrosion inhibition and microbiological control. The DE developer has subsequently employed similar large, stratified TES installations at several additional DE developments around the country. Those installations include one that entered initial operation in 2003 rated at 160,000 ton-hours in chilled water service (with pre-designed expandability to 250,000 ton-hours when ultimately converted to low-temperature fluid service). [ABSTRACT FROM AUTHOR]