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Micro combined heat and power (mCHP) is an emerging technology that can simultaneously produce onsite heat and power for residential, light commercial and industrial applications. These systems operate in parallel with the grid or islanded from the grid and in conjunction with other equipment to supplement or meet building power and thermal loads. mCHP systems can be integrated with other appliances to minimize operational costs by improving the overall system efficiencies as well as reduce greenhouse gas emissions associated with residential space conditioning and water heating. Such integrated energy systems (IESs) include a myriad of equipment combinations in addition to the mCHP, such as renewable power sources, thermal and electric energy storage, as well as traditional equipment such as furnaces, water heaters and heat pumps. IESs can be implemented in nanogrid configurations that allow for self-sustained HVAC and water heating independent of grid power. However, many nano-grid systems are designed around autonomous backup generators that do not operate in parallel with other power sources such as the grid. These systems often integrate the backup generators with renewable photovoltaics and battery storage that can be oversized due to intermittency and short-term operation of backup generators. This paper will discuss challenges and solutions associated with grid-tied and off-grid mCHP applications that use various nano-grid controllers to integrate mCHP systems with other bi-directional power sources, hybrid electric and fuel-fired HVAC and water heating systems, electric vehicle charging, and thermal and electric energy storage in Residential homes. The paper identifies potential benefits of interactive nanogrid or microgrid features that manage power and thermal sources and loads in real time to maximize efficiencies, minimize greenhouse gases and minimize operating costs. [ABSTRACT FROM AUTHOR]

This paper describes the investigation of heat pumps for GreenSCIES, a 5th Generation heat network in Islington, London. The paper describes the GreenSCIES concept integrating Mobility, Power and Heat into a local energy system. At the heart of the system is a 5th generation heat network, which utilises an ambient heat network to capture secondary heat and share heat between different applications. The GreenSCIES network, technology utilised and buildings connected are described. Heat pumps are used to amplify the temperature of the ambient loop to deliver heat at the required temperature in connected buildings. A number of different heat pumps using different refrigerants and configurations were appraised in this study. This considered the performance, safety, environmental impact, operational and capital expenditure point of view. The study shows the importance of heat pump COP on the economics of operating the system and suggests innovative series arrangements in order to improve performance and economics. [ABSTRACT FROM AUTHOR]

This paper, concerned with the low and ultra-low-temperature district heating goals of several countries for decarbonization, reveals the temperature mismatch between existing heating and cooling equipment and the thermal supply. The industry and the energy sector aim to resolve this conflict by total electrification with renewables and heat pumps for temperature peaking and, or equipment oversizing. This study shows that both measures defeat the purposes of decarbonization and quantify the carbon dioxide responsibility in embodiments and during operation according to exergy destructions. It has been concluded that widely available but with low exergy waste and solar energy resources can be mobilized for decarbonization in the building sector only with temperature-compatible heating and cooling terminal units minimizing the temperature mismatches. In this respect, a new panel radiator with heat pipe technology, which can satisfy indoor thermal loads with supply temperatures as low as 35oC (95oF) and sensible cooling loads as high as 19oC (292 K, 66.4oF) with little oversizing, is introduced. Test results from the ASHRAE Standard 138 are discussed. [ABSTRACT FROM AUTHOR]

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 transformation of voltages leads to two types of energy losses in the form of heat, namely no-load losses which are inherent to the transformer and associated with its core; and load losses, caused by the resistance of the windings, which are a direct function of the electrical loading. This paper investigates how the waste heat generated by electrical transformers could be captured and reused via district heating networks. At first, the current availability of waste heat from transformers in the UK is assessed based on data from distribution network operators (DNOs). Potential methods for recovering waste heat from transformers are then presented, and the achievable benefits are discussed based upon carbon and cost savings against conventional heating technologies. [ABSTRACT FROM AUTHOR]

In the continuing search for economical and low carbon solutions to heating systems in cool climates, designers often turn to heat pumps, including air source units. Hydronic distribution has a number of advantages particularly when longer distances are encountered. Capacity does not always come cheaply, even using air source equipment, and electrical demand costs can diminish the operating cost benefit of heat pumps. Utilization of a hybrid heat pump/conventional heating system can mitigate these disadvantages while still providing benefits of a low carbon heat source. This paper describes the use of a conventional air cooled chiller/heat pump in a low temperature hydronic heating system for a public works garage/vehicle storage area, its design, commissioning, and first year's operating experience. It will describe the approaches taken to maximize the efficiency of the heat pump by minimizing required water temperatures, including radiant floor heating and high capacity fin tube and air coils. The utilization of the backup heating source to minimize installed cost, control electrical demand charges, and provide system redundancy will be described. Finally, the challenges of using fairly conventional air cooled equipment for cold climate heating will be described. Defrost cycle control and actual heating Coefficients of Performance will be examined using data from the building automation system. With the promise that this equipment holds in this application, it can be hoped that advancing technology and controls can make this a viable off the shelf solution from domestic suppliers to future low carbon heating system designs, particularly when the added cost of water source applications seems out of reach. [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]

Thermal energy systems’ resilience is especially important for extreme climates, such as arctic or tropical environments. While metrics and requirements for availability, reliability, and quality of power systems have been established (DOD 2020), similar metrics and requirements for thermal energy systems are not well understood. In one of the first attempts to address this deficiency, a study was conducted to better understand the level of reliability required for energy supply systems that will be capable of supporting environmental conditions required for the facility’s mission, the comfort of people, and sustainment of a building in arctic environments under predominant threat scenarios. This paper is split into two parts. The purpose of Part I is to present the methodology and results of a unique temperature decay test conducted during the winter, along with blower door tests on five representative military buildings in Alaska. In Part II, the modeling analysis is compared and calibrated to the experimental data collection for the thermal decay test (TDT). A reliable building model allows us to predict the maximum time available to repair the heat supply system before the building needs to be evacuated, when damage is done to equipment or facilities critical to the building operations, or when damage is done to the building itself. This will provide guidance to building managers on evacuation and sustainment procedures for buildings in arctic climates that are affected by fuel or electrical disruptions. [ABSTRACT FROM AUTHOR]

In cold-climate multi-family (MF) buildings, space and domestic hot water heating often account for over half of total building energy use. Reducing the energy use of these systems can reduce GHG emissions as well as operational energy costs. Literature suggests that boiler equipment tends to operate at lower efficiencies when demand is low compared to the boiler capacity, however, investigation into this phenomenon has been limited in high-rise MF buildings, particularly in the Canadian context. This paper expands on previous work by the authors to characterize central heating plant performance in MF buildings. Building Automation System (BAS) data from four Ontario MF buildings are used to develop natural gas consumption, boiler utilization factors, and cycle length profiles. Longer cycle lengths were observed in the MF Buildings with smaller, single- or two-stage boilers (ranging from 37 minutes in the summer to 535 minutes in the winter) as compared to the MF Buildings with larger, fully modulating boilers, which typically had cycle lengths of 20 to 30 minutes. An analysis of space heating system efficiency in the buildings revealed annual system efficiencies between 41% and 47%, significantly below the boiler nameplate efficiencies of 80% and above. The large, fully modulating boilers installed in two of the buildings did not offer improved performance over the smaller, single- or two-stage boilers installed in the other buildings - each system demonstrated reduced efficiency at low building demands. [ABSTRACT FROM AUTHOR]

This paper describes the development of a building technology system for a residential building complex built in 1985 in the city of Salzburg, Austria. The settlement consists of 75 apartments and is in great need of renovation. In the context of this survey, an extensive refurbishment and densification is conducted. Due to high costs caused by the construction and maintenance of a ventilation system, it is state of the art in Austria to install a simple exhaust ventilation system without implementing a heat recovery system. One of the main goals is targeting CO2 reduction by developing a system which combines the benefits of an exhaust ventilation system without heat recovery and a monitored mechanical ventilation system including a central heat recovery system. The required ventilation for each room is provided by overflow openings in the façade, with its benefits to avoid air filter change in comparison to a ventilation system. The novelty is obtained by the exhaust air heat recovery system via an air to brine heat exchanger in combination with a drain water heat recovery system as a heat sources for the conducted heat pumps. The renovation concept is a holistic approach combining the fields of energy, mobility, social structure and the economics of social housing. A monitoring system, which is implemented during the construction phase, is gathering measurement data concerning the performance of the refurbished buildings and should provide information of possible factors to increase efficiency of the system. The developed refurbishment concept will be documented and transferred for an implementation into other residential complexes which are in need of renovation. Performance of the building and its combination with different heating and ventilation systems will be evaluated within the simulation environment IDA ICE Version 4.8, in order to identify possible benefits of the innovative heating system including an exhaust heat recovery system and a drain water heat recovery system. As a result of the simulation, a comprehensive comparison between the systems in terms of CO2 emissions and energy efficiency is conducted. [ABSTRACT FROM AUTHOR]

Radiant cooled floors have been successfully used on many projects over the past fifteen years, and many ASHRAE, as well as other peer-reviewed, papers have been written on these projects. The convective cooling performance of a cooled floor has been reported by Olesen and Simmonds; Borressen (1994) reported on the solar absorption of a radiant cooled floor, which was further reported by Simmonds, Gaw, Holst, and Reuss (1996), Simmonds (2006). With this research, the performance of different types of flooring could be predicted to see which ones responded to radiant cooling the best. This paper explains the performance of each type of commonly used floor and analyses the results from a model that predicts the conditions created by each flooring type. [ABSTRACT FROM AUTHOR]

The Air-Conditioning, Heating, and Refrigeration Institute (AHRI) announced an industry-wide cooperative research program to evaluate alternative refrigerants that have low global warming potential (GWP). This paper presents testing results for the performance of an air conditioner and a heat pump using three low GWP refrigerants (R32, D2Y-60 and L-41A) and R410A. The results show R32 and L-41A are good replacement candidates for R-410A. The paper also presents thermophysical property differences the four refrigerants. The paper also presents the cycle modeling which was used to investigate soft-optimization for D2Y60. [ABSTRACT FROM AUTHOR]

This paper describes a portion of a study which investigated the reduction of energy consumption in grocery stores in a hot and humid climate. The first part of the study investigated the maximum possible savings that can be obtained by implementing energy efficiency measures (EEMs) in a grocery store. The second part of the study took a step further and examined the option of combined heat and power (CHP) technologies to further reduce the energy consumption of the grocery store. In this paper, several energy efficiency measures (EEMs) for the grocery store were examined to reduce the overall energy consumption of the store. A calibrated whole-building energy simulation model was used to carry out this analysis. The EEMs were organized into four categories, which include measures for the envelope; lighting and daylighting; heating, ventilation, and air conditioning (HVAC); service hot water (SHW) systems; and refrigeration systems. Only certain measures were selected under each category depending on the simulation capabilities of the whole-building simulation program selected for the analysis. The measures were first assessed individually and then combined to provide a cumulative energy savings based on each category. Savings were assessed in terms of both site and source energy consumption. EEMs for the building envelope were found to be least effective of all the measures considered by this study. Savings for site energy consumption in this category were in the range of -0.3% to 3.1% and for source energy consumption were in the range of -0.20% to 2.3%. Savings for site energy consumption on implementing EEMs for lighting and daylighting were in the range of 4.3%to 5.4%and for source energy consumption were in the range of 7.5% to 9.7%. Savings from implementing EEMs for the HVAC systems for site energy consumption were in the range of 0.2%to 12.1% and for source energy consumption were in the range of 0.1% to 4.9%. Savings from implementing EEMs for refrigeration systems for site energy consumption were in the range of 0.1% to 16.9% and for source energy consumption were in the range of 0.1%to 9.2%. Selected measures when grouped together provided site energy savings of 57.9% and source energy savings of 55.8%. [ABSTRACT FROM AUTHOR]

This paper presents the overview of the currently practiced new housing constructions in Ontario based on a survey to local homebuilders in the Greater Toronto Area (GTA), which was conducted as part of the proposed methodology to determine the suitability of the potential optimal upgrades considered for the analysis. Also presented in this paper is the economic feasibility study of the identified optimal upgrades from the survey for the selected cities in Ontario with varying climatic conditions. Based on the results of the survey, it was concluded that the participant builders have already implemented or considered for implementation some of the advanced technologies into their current building practices to achieve the energy performance level that exceeded the minimum requirements as specified by the existing Ontario Building Code (OBC). Furthermore, the results of the economic feasibility study showed that, based on the life cycle analysis of 30 years, the combination of optimal upgrades comprised of increasing the thermal resistance of the building envelope components, and installations of the most energy-efficient heating, ventilating, and air-conditioning (HVAC) system could achieve up to 31% reduction in both the estimated total annual energy consumption and greenhouse gas (GHG) emissions in comparison to the same building configuration, but built in accordance with the OBC, and without the implementation of the identified optimal upgrades. Furthermore, with the installation of a residential photovoltaic (PV) system combined with these upgrades, the estimated total profit of up to $89,035 could be achieved through Ontario's micro Feed-in-Tariff (FIT) program, allowing a homeowner to pay for the installation of additional upgrade(s) to further improve the energy efficiency level of a home, ultimately reaching the net zero energy status. [ABSTRACT FROM AUTHOR]

This paper examines several methods for calculating heating and cooling degree-days to any base by relying on temperature statistics such as the monthly mean temperature and the standard deviation of daily average temperature. It is found that the method developed by Schoenau and Kehrig works best, and is usually able to estimate monthly heating and cooling degree-days to within 3°C/day or 5.4°F/day (in a root-mean-square error sense) of their true value. The method clearly outperforms other widely used methods, such as the one derived by Erbs et al. (1983). The paper also presents an extension of the Schoenau and Kehrig method to the case when only monthly mean temperatures are known. [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]

Liquid-to-air coils used as air heating system coils and air system cooling coils for air-conditioning, refrigeration etc. rarely use their design capacity. The capacity must therefore be reduced accordingly, traditionally by means of on-off operation or by means of control valves. Draw-backs of traditional control are excessive pressure drop and drive power to pumps due to high flows as well as the need for balancing valves and control valves with authority. There are, however, possibilities to substantially reduce the drive energy of pumps and fans for air coils, e.g. by replacing valve and damper control by direct control of decentralized pumps and fans. This may achieve better control at a lower cost while using substantially less drive energy. This paper includes basic analysis of heat transfer and control methods to study how coil design affects the transfer function of an air coil on capacity turn-down. The analysis indicates that direct flow control, using variable-speed pumps, may require only a fraction of the drive power needed by traditional valve control. Furthermore, system designs for low flow rate and pressure drop also provide opportunities for new types of laminar-flow coil designs. Results show that the transfer functions of alternative control methods for the capacity and outlet temperatures of air coils can be written as simple functions of the controlling variable (supply temperature, inlet temperature or coil liquid flow rate). The transfer functions may be tailored to specific needs by changing design parameters such as the design values of air and liquid flow rate and the heat transfer characteristics and heat transfer areas of the respective air and liquid sides. Also, the paper provides an example of alternative system design and control strategy. [ABSTRACT FROM AUTHOR]

The validation process and result of a dynamic air handling unit (AHU) model (referred to as 1312 model hereafter) are discussed in this paper. The development of the 1312 model is summarized in a companion paper. Strategies to validate the model using experimental data mostly from common system operations are designed. If problems were identified using system operation data, follow up component model calibration is used to modify and improve the model. A series of experiments were designed and implemented to obtain pressure resistance parameters for the supply duct system and mixing box dampers. Building operation data from winter, summer, and spring seasons were used to validate the 1312 model. Good agreements were achieved between experimental data and simulation outputs for the 1312 AHU model, especially for summer and winter seasons. When using 1312 model to simulate AHU operation for spring season conditions, simulated outdoor and supply airflow rates and supply air temperature, while tracking experimental data, showed certain level of oscillation. [ABSTRACT FROM AUTHOR]

Experiments with a fan-driven convector used for both heating and cooling are described in this paper. Only the cooling situation is considered. The convector is positioned in the upper corner of the room, and from there the cold air is let out through the device along the ceiling. The airflow coming from the diffuser is partly controlled by the momentum flow and partly from gravity forces, where the thermal load in the room and the temperature difference between room air and supply air affect the airflow from the convector The convector system was tested in the same test room in which many regular ventilation systems were tested earlier to be able to compare airflow from the convector system with regular ventilation systems at a later stage of this research. The heat load in the room consists of a thermal manikin sitting at a desk, a computer, and a desk lamp producing a total heat load of 210 W From the measurements, limitations for the fan-driven convector are set up in a design graph based on flow elements from the convector a maximum velocity assumption, and a critical vertical temperature gradient in the room. The limits for the curves in the design graph are found by analyzing the acceptable conditions for the supply flow rate and the temperature difference for the convector system. The paper shows that the air distribution from the convector results in comfortable velocity and temperature conditions with a heat load of 210 W. This is also confirmed by the draft ratings, which in all the experiments are below 14%. The limit of the cooling capacity of the convector is reached if the heat load in the room is increased to approximately 350 W, and from the design graph it is found that in this case it will be difficult to obtain a comfortable situation in the room without draft. [ABSTRACT FROM AUTHOR]

This paper presents a new methodology for screening measured data from buildings where heating, cooling, and electricity consumption are separately recorded. It defines energy balance load (EBL) as the difference between the heating requirements plus the electric gains in the building and the cooling coil loads. It then applies first law energy balance in conjunction with the concepts of analytical redundancy, trend checking, sensitivity, and uncertainty analysis to develop a methodology using measured values of EBL to identify bad data. This paper is the first part of a two-part series; it presents the theoretical basis for the methodology and illustrates its use on samples of measured building data. In part two, a program that was created to automatically pre-screen the measured building energy consumption data by utilizing EBL methodology and case studies will be introduced. [ABSTRACT FROM AUTHOR]

In modeling and simulation of real building and heating, ventilating, and air-conditioning (HVAC) system configurations, it is frequently found that certain parts can be represented in one simulation software, while models for other parts of the configuration are only available in other software. However, very often quality assurance dictates that the configuration should be modeled in an integrated fashion due to thermodynamic and other interactions between the various subsystems. This paper gives an overview and presents initial results of an ongoing research project that aims to improve the applicability and use in a design context of building performance simulation software by addressing this problem. The objective of the work is to research, enable, and validate run-time external coupling of distributed building and system simulation software. Although the research uses specific simulation environments, the coupling mechanism(s), data-exchange procedure, and protocol(s) that are being developed ensure that the approach has a wide and general applicability. This paper also discusses some of the domain-specific theoretical and numerical issues regarding run-time interoperability and parallel coupling of distributed HVAC component models. A prototype is presented. The initial results for a practical case study are used to demonstrate the prototype and to illustrate the usefulness of the approach. The paper concludes with indicating directions for future work. [ABSTRACT FROM AUTHOR]

This paper offers a guide for the design of water-based embedded heating/cooling systems to promote the use of renewable energy sources and provide a method for actively integrating the building mass to reduce peak loads, transfer heating/cooling loads to off-peak times, and decrease system size. Peak loads can be reduced by activating the building mass using pipes embedded in the main concrete structure of the building—a thermo-active building system (TABS). For these types of systems, the steady-state calculation of heating and cooling capacity is not sufficient to evaluate the cooling capacity in practice. The dynamic behavior can be evaluated by full dynamic computer simulations of buildings with systems. This is, however, often regarded as too complicated and takes too much time in the design phase. Therefore, this paper presents a simplified method that is being implemented as a European standard. The proposed methods are used to calculate and verify that the cooling capacity of the system on the room side is sufficient to keep the room temperature under a given criterion. The method also calculates the cooling requirement on the water side, which is needed for sizing cooling systems, including the chiller. [ABSTRACT FROM AUTHOR]

This paper describes results of recent laboratory tests on PEX-aluminum-PEX hot water distribution system piping and compares them to previous test results on rigid copper pipe. These tests allowed calculation of measured piping heat loss (UA) factors under a variety of different temperature and flow conditions, with various insulation levels. Several unanticipated flow regimes were observed, causing results not to behave as would be expected using fully developed flow theory. This piping UA information can be used to estimate piping heat loss and steady-state temperature drop under any desired temperature and flow conditions. The UA data can additionally be used to determine piping cool-down rates after flow has ceased. Piping heat loss data are one critical part of the information necessary to accurately estimate total energy losses associated with piping systems. This paper includes examples of how to use heat loss information to estimate energy loss effects due to heat loss from piping. These energy loss effects extend beyond just energy loss from the pipe itself and include, for example, increases in tank heat loss caused by the need to set temperatures higher to overcome temperature drop of water flowing through the pipe. [ABSTRACT FROM AUTHOR]

Floor heating has been the most basic version of panel heating and cooling systems since ancient times. Recently newer applications are becoming widely used, especially in Europe. For all panel applications, whether the most basic or the most innovative, their attributes are mainly focused on energy efficiency and better comfort. So far, little attention has been paid to their exergy efficiency, which in fact is a more insightful means of analyzing and comparing HVAC systems to optimally resolve the quadrilemma of human comfort, environment, energy, and economy. This paper shows that panel systems, especially when coupled with a convective component in a hybrid HVAC panel, are more exergy-efficient when they are tied into low-exergy energy sources. A typical analysis for a residential home indicates that the exergy efficiency of a hybrid panel utilizing a low-enthalpy energy resource and a heat pump is almost tenfold higher than a forced-air system utilizing natural gas and grid electricity. This paper draws an energy-based roadmap for the next-generation HVAC systems. [ABSTRACT FROM AUTHOR]

Radiant cooled floors have been successfully used on many projects over the past ten years, and many ASHRAE and other peer-reviewed papers have been written on these projects. However, many questions still arise regarding the performance of radiant cooled floors when subjected to solar radiation. The convective cooling performance of a cooled floor has been reported by Olesen (1994) and Simmonds (1994); Borressen (1994) reported on the solar absorption of a radiant cooled floor, which was further reported by Simmonds, Gaw, Holst and Reuss (2000). Even with this research, many questions are still being raised regarding the performance of a radiant cooled floor when absorbing solar radiation. This paper explains the performance of the floor, including some limitations of the presented calculation method and information on controllability. [ABSTRACT FROM AUTHOR]

This paper describes the second step toward development of an affordable net zero energy house as part of the Department of Energy's Building Technology Program. Building affordable houses that generate as much energy as they use is the long-term goal of that program. The house discussed in this paper is located in Lenoir City, Tennessee. A Habitat for Humanity family of three took occupancy in December 2003. This all-electric house has airtight structural insulated panels (SIPS), high-efficiency windows with a 0.34 U-factor and 0.33 solar heat gain coefficient, a SEER 14 heat pump, a space-integrated heat pump water heater, and a 1.98 kWp grid-connected solar photovoltaic system. Together these features, which cost less than $100,000 to construct, have led to an annual total energy cost of $0.88 per day after utility solar credits. Thirty-two sensors were installed in the house to monitor thermal comfort, energy-efficient technologies, and the rooftop photovoltaic system every 15 minutes for longer than a year. Twenty-three percent of the total energy demand of the house is satisfied by the solar photovoltaic system. [ABSTRACT FROM AUTHOR]

A component-based model for residential air conditioner and heat pump energy calculations has been developed through ASHRAE Research Project 1197. A primary objective of this project was to develop a suitable model that requires only readily available, or potentially readily available, input data. The component model meets this objective by only requiring rating data that are generated from ARI Standard 210/240. Unfortunately, only a small percentage of the data collected during these tests is published by ARI. Some manufacturers release a more significant portion of the test data in their technical literature, but these data are often incomplete. This paper describes the development of default data for the modeling of residential air conditioners and heat pumps using a test suite of 25 units. The paper evaluates the impact of limited data availability, and the need to use default data, on model prediction accuracy. The results show that the use of minimal data often produces acceptable results, though accuracy improves significantly with additional rating data. Of most importance are the power at standard rating conditions, the type of compressor, and the coil airflow rates. The results also show that accurate results are obtained without knowing the exact compressor model number. [ABSTRACT FROM AUTHOR]

Variable air volume (VAV) terminal placement has typically been considered ‘good enough’ in the HVAC industry, regardless of upstream duct geometry that clearly affects the response of the flow sensor. This paper describes the loss of VAV flow sensor amplification, uniformity, and precision following common upstream duct geometries from a recommissioning standpoint. Two brands of VAV terminals were tested in three different sizes: 250, 200, and 150 mm diameters (referred to as 10, 8, and 6 in. throughout this paper). Upstream geometry was modeled after transitions that were deemed ‘poor’ during a recommissioning procedure that was completed at three facilities during ASHRAE Research Project 1137. The ‘poor’ upstream conditions included combinations of concentric reducers, expanders, 90° elbows, and S-shape geometries with varying straight duct lengths prior to the sensor. This paper outlines some basic recommendations that HVAC designers, terminal manufacturers, and commissioning agents can use to improve the accuracy of VAV airflow sensors both before installation and as part of a recommissioning procedure. [ABSTRACT FROM AUTHOR]

Ventilation standards and guidelines typically treat ventilation as a constant and specify its value. In many circumstances, a designer wishes to use intermittent ventilation rather than constant ventilation, but there are no easy equivalencies available. This paper develops a model of efficacy that can determine how much intermittent ventilation is needed to get the same indoor air quality (IAQ) as the continuous value specified. This paper describes a simple relationship between three dimensionless quantities: the temporal ventilation effectiveness—which will be called the efficacy—the nominal turnover, and the underventilation fraction. This relationship allows the calculation of intermittent ventilation for a wide variety of parameters and conditions. The relationship can be used to define a critical time that separates the regime in which ventilation variations can be averaged from the regime in which variable ventilation is of low effectiveness. The paper shows that ventilation load-shifting, temporary protection against poor outdoor air quality, and dynamic ventilation strategies can be quite effective in low-density buildings such as single-family houses or office spaces. The results of this work enable ventilation standards and guidelines to allow this extra flexibility and still provide acceptable indoor air quality. [ABSTRACT FROM AUTHOR]

The paper describes a model-based approach to automated functional testing at the component level and presents results from preliminary field testing of a prototype software tool that implements the method. The method is based on an integrated life-cycle approach to HVAC commissioning and performance monitoring. The tool uses component-level HVAC equipment models implemented in an equation-based simulation environment. When used for commissioning, each model is configured using design information and component manufacturers' data. Once an acceptable functional test has been performed, the model is fine-tuned to match the actual performance of the equipment by using data measured during the functional test. The fine-tuned model is then used in routine operation for on-line monitoring and fault detection. The paper describes the method and reports test results from HVAC secondary systems in a commercial building and an experimental facility. [ABSTRACT FROM AUTHOR]

This paper provides an overview of the current design procedures of surface water heat pump (SWHP) and direct cooling (DC) systems with an emphasis on the key role of water temperature data in the design process. The paper gives an overview of the current information on SWHP .systems readily available to HVAC design engineers. An overview of the temperature data collection process is discussed. Specific temperature plots are given from different regions of the country to show how water temperature changes with depth and season in those regions. [ABSTRACT FROM AUTHOR]

In this paper, a transient numerical model for a radiant floor panel is integrated into a whole-building simulation program and utilized to evaluate various control strategies. Both conventional and optimal control strategies for hot-water radiant floor systems applied to residential buildings are considered in this paper The optimal controls are developed to maintain an acceptable thermal comfort level for occupants and to reduce heating energy cost. It is found that the optimal controls have the potential to save up to 30% of heating energy use compared to conventional controls. However, the performance of optimal control strategies depends on several design and operating conditions. [ABSTRACT FROM AUTHOR]

ASHRAE Research project 1273-RP recalculated and expanded the tables of climatic design conditions in the ASHRAE Handbook—Fundamentals. These tables provide values of dry-bulb, wet-bulb, and dew-point temperature, enthalpy, and wind speed at various frequencies of occurrence over annual and monthly periods and for some of these, mean coincident values of other variables of interest. Compared to the previous edition of the Handbook, the new tables include additional elements and are calculated for a much greater number of stations over a longer period of record. This paper explains the procedure used to compute the design conditions, the data sources used, the techniques employed to screen out erroneous data, and the completeness criteria required by the calculation- It also provides a summary of the stations included in the 2005 Handbook and a brief description of how the new values compare to those published in the 2001 edition. Finally, the paper provides an overview of the capability of the Weather Data Viewer, a companion CD-ROM that gives full access to the frequency information used to compile the tables of climatic design conditions. [ABSTRACT FROM AUTHOR]

The recent ASHRAE project, "Updating the ASHRAE/ACCA Residential Heating and Cooling Load Calculation Procedures and Data" (1199-RP), developed two new residential load calculation procedures: residential heat balance (RHB), a detailed heat balance method that requires computer implementation, and residential load factor (RLF), a simplified procedure that is hand tractable and suitable for spreadsheet implementation. This paper describes RHB and its development. For calculation of sensible cooling load. RHB applies the general approach of the ASHRAE heat balance (HB) method, based on room-by-room 24-hour design-day simulation. The 24-hour procedure eliminates issues of gain diversity that are troublesome in prior single-condition methods. RHB includes algorithms for calculating sensible cooling loads with temperature swing (temperature excursion above the cooling setpoint) and to handle master/slave control (room cooling controlled by a thermostat in another room). RHB is implemented in the ResHB FORTRAN 95 application, developed by modification and extension of the ASHRAE Loads Toolkit. The paper documents RHB/ResHB models and modeling assumptions. Because RHB is a first-principles heat balance procedure, it can be directly validated and refined using empirical data. [ABSTRACT FROM AUTHOR]

This paper discusses the development of a methodology to quantify window performance on human thermal comfort with eight case studies of different window systems. The methodology is based on the Building Comfort Analysis Program that was developed during ASHRAE research projects 657 and 907. Human thermal comfort is achieved by maintaining a heat balance between the human body and the environment. This is accomplished by convection and radiation. In a room there are other associated issues, such as conduction through the walls, convection past the walls, and radiation between the various surfaces, that will influence comfort. The presence of a window system adds complexity to the problem as they have different optical and thermal properties. This paper expands on the existing three-dimensional mathematical model by incorporating a method to read in a user-defined window and also read in the properties obtained from the widely available Window 5.1™ program. A representative case study is analyzed to illustrate the means of quantifying the results. Results have been quantified as percentage of comfortable floor area. [ABSTRACT FROM AUTHOR]

This paper discusses the development of a methodology to quantify the impact of fenestration systems on human thermal comfort with a representative case study. The methodology is based on the Building Comfort Analysis Program that was developed during ASHRAE research projects 657 and 907. Human thermal comfort is achieved by maintaining a heat balance between the human body and the environment. This is accomplished by convection and radiation. In a room there are other associated issues, such as conduction through the walls, convection past the walls, and radiation between the various surfaces, that will influence comfort. The presence of fenestration systems adds complexity to the problem as fenestration products have different optical and thermal properties. This paper expands on the existing three-dimensional mathematical model by incorporating a method to read in a user-defined fenestration system and also read in the properties obtained from the widely available Window 5.1™ program. A representative case study is analyzed to illustrate the means of quantifying the results. Results have been quantified as a percentage of comfortable floor area. [ABSTRACT FROM AUTHOR]

An analytical study is carried out to assess the impact of corrections to nominal test conditions on the measured energy factor for residential water heaters. While test conditions are specified in the method of test, the difficulty in exactly achieving these test conditions in the laboratory necessitates a computational approach to correct the results to nominal conditions. This paper examines the magnitude of those corrections for a range of water heaters of various fuel type, heating method, and size across a number of potential draw volumes during a 24-hour simulated use test. In making these corrections, a recovery efficiency and a standby heat loss coefficient are determined during the test; the effects of variations in those measured values on the resultant energy factor are discussed. Finally, the impact of tighter test tolerances on the variability of the energy factor is investigated to assist in evaluating the benefits of changing test conditions. [ABSTRACT FROM AUTHOR]

District cooling plants using large electric-powered water-cooled vapor compression machines in warm weather regions are gaining popularity, providing an economic mass scale cooling for buildings. This paper proposes to replace such a system with the use of direct-fired two-stage absorption chillers located at thepowergeneration plant. Absorbers energized by the exhaust of a gas turbine power generation plant can be used to provide chilled water to cool nearby buildings. Calculations are included that demonstrate how the carbon footprintcanbereducedandtheeconomicgains involved. Also included is a sustainable design approach addressing environmental, economic, and social aspects. The methodology is as follows: A stepped schematic procedure was adopted to show how calculations were carried out. Industrial gas turbine engine data were used in conjunction with standard data and equations given in ASHRAE standards. Calculations presented in this document can be used to analyze the feasibility of such an investment. The results were obtained and analyzed on sustainable bases, discussing the environmental, economic, and social gains associated with such a design. Theanalysis demonstrateshowsuchasystem canbe sized, how sustainable energy development can be achieved with substantial reductions in the carbon footprint, and the profit gains. Equations were developed assessing capital investment returns and generated profits, providing a guide on the feasibility of such investments. [ABSTRACT FROM AUTHOR]

The required length of vertical ground heat exchangers (GHX) used in ground-coupled heat pump (GCHP) systems is determined so that the outlet temperature from the GHX remains within certain limits for the worst ground load conditions. These conditions may not necessarily occur after 10 or 20 years of operation, as is usually assumed, but often occur during the first year of operation. The primary objective of this paper is to develop a general methodology for the calculation of the total required bore field length on a monthly basis during the first year of operation using the framework of the ASHRAE bore field sizing method. It is a three phase process. The first phase consists of analyzing andorderinggroundloads according to the firstmonthof operation. Next, afirst set of required lengths is determined by using the analyzed ground load components and assuming a temperature penaltyTp=0. Then, aniterative process to calculate the temperature penalty at the end of each month is carried out to obtain the final required length for the worst conditions. The methodology is exemplified in a particular case with a slight annual cooling thermal imbalance and with a high influence of the hourly peak in heating. For this particular case, it is shown that the required bore field length occurs during the first year and that the starting month of operation has a strong influence on the results. Finally, it isshownthat it is possible toreduce the borehole spacing when the annual ground load is quasibalanced. In the case studied here, the minimum length occurs for a boreholeto- borehole spacing of about 3.2 m (10.50 ft). [ABSTRACT FROM AUTHOR]

The B&O Bad Aibling Park, located in Bavaria, Germany, occupies a 173-acre (70 ha) facility that originally served as an airbase. Although the site buildings were in good repair, their thermal quality was poor . The district heating system was in good condition, but the scale of heat generation was too large. This project described in this paper designed a development plan that could be easily replicated and that could ultimately become a model for a zero energy city. The B&O Bad Aibling Park project employed a rich diversity of technologies that may be scaled up for application in larger urban areas. A biomass-fired boiler and a number of decentralized solar thermal facilities feed heat into an existing district heating grid in combination with grid-fed heat pumps that generate hot water individually in buildings and that use central and decentralized hot water storage tanks. This configuration allows the system to operate with low grid temperatures, and makes use of optimized energy efficiency measures while intensively harvesting solar energy. The B&O Park model project is a test bed, small enough so that it can address questions and problems in a purposeful way, yet large enough to set a standard that can be readily used in other urban areas or military installations. [ABSTRACT FROM AUTHOR]

HVAC systems are different in terms of cost and performance. Their behavior in each single room or building is unique and depends on many factors, including the system type, the diffusers characteristics (the number, locations, and type of diffusers), the quality of dampers used, the thermostats' locations, the inside design temperature (thermostat setpoint temperature), and the control scheme associated with the HVAC system. Similarly, the building energy demand prediction is also unique, depending on the HVAC system design, the characteristics of building envelope and weather, people's behavior, and so on. This paper investigates the possibility of improving the heating energy demand calculation accuracy of a building equipped with an electric floor radiation system by the integration of a zonal model into a multi-room thermal model. Three thermostat setpoint strategies, room air temperature (RAT), mean radiant temperature (MRT), and operative temperature (OT) have been studied. Comparisons between the predictions of the thermal multi-room model and the integrated zonal model POMA/multi-room model developed have been performed to demonstrate the importance of considering the room temperature distribution in energy predictions. As well, detailed prediction of thermal comfort (PMV and PPD indices) allows the prediction of the relationship between thermostat locations, energy consumption, and thermal comfort. [ABSTRACT FROM AUTHOR]

The Fort Carson, CO, Combat Aviation Brigade (CAB) complex is a proposed 60-building development originally planned as a grouping of individual structures, each with its own boilers and chillers. None were to be engineered to share energy resources with neighboring structures. After the initial planning for the CAB, the US Army named Fort Carson as one of eight pilot net zero installations for energy use as a part of the Army's overall effort to conserve resources. Fort Carson's goal for the CAB complex at Butts Army Airfield consequently became the construction of a "net zero ready" community of buildings designed to optimize energy performance, water conservation, and waste diversion. The US Army Engineer Research and Development Center, Construction Engineering Research Laboratory (ERDC-CERL) conducted a study to assess the potential for synergy between CAB facilities energy needs and the feasibility of building a Central Energy Plant (CEP) that would produce hot and chilled water to be used for heating and cooling throughout the CAB complex, and that could also generate electricity through cogeneration. This paper describes the results of the study and different alternatives considered, as well as energy requirements and specific technologies that have been applied to this new generation of buildings. [ABSTRACT FROM AUTHOR]

Increasing occurrences of record high temperatures, hot spells, and deadly heat waves in recent years have warranted a growing global concern with overheating in buildings. This paper demonstrates how two proposed measurements designed to quantify overheating exposure duration, an important aspect of thermal health that has not been addressed by the existing overheating risk assessment approaches, can be used to inform the selection of retrofitting options in places with continental climates such as Chicago where both the cooling and heating seasons are challenging. The two measurements -- consecutive hours of exceedance (CHE) and cumulative degree exceedance of continuous exposure (CDECE), allow an assessment based on continuously overheated intervals (COI) that more appropriately capture the state of overheating as relevant to the occupants' thermal health than does aggregated assessment which is easily influenced by how thresholds and occupancy schedule are defined. In the context of a typical pre-1942 single-story uninsulated timber-frame Chicago bungalow, as simulated in this study, although wall insulation is found to be more effective than roof insulation in the winter, there is little difference in the overheating risk reduction potential of the two in the summer. However, when wall insulation is applied in tandem with roof insulation, thermal performance is improved in both seasons. Further analysis is needed to investigate the energy and cost savings of these upgrades. More broadly, given further epidemiological understanding of heat-related morbidity and mortality, CHE and CDECE may aid in the identification of potentially health-threatening building stocks within a city or region, and in the selection of appropriate retrofitting options to reduce heat-related health risks in buildings. [ABSTRACT FROM AUTHOR]

Aftermarket boiler control systems offer a potential option for energy efficiency retrofits of commercial gas-fired boilers. These devices are installed on existing boilers with no interruption to boiler operation. The systems monitor boiler operation and adjust boiler cycling rates to reduce annual fuel consumption. Aftermarket boiler control systems are seeing initial market and technical success and thus, are candidates for utility-sponsored energy efficiency programs. Through a third-party laboratory evaluation of an aftermarket boiler control system, preliminary data reported from this study quantify the fuel savings under a range of heating demand profiles. A laboratory test stand is developed to deliver a variable heating load to the test boiler in order to simulate a typical building installation. The Department of Energy (DOE) Energy Plus model, using the standard reference building model of a secondary school, is used to create a 24-hour heating demand profile for typical commercial buildings. Boiler operation and energy consumption is monitored under both steady-state heating loads and 24-hour simulated heating demand profiles. Fuel consumption is measured with and without the aftermarket control system to determine the reduction in burner cycles, fuel savings, and system temperatures. Under most conditions, the aftermarket control system reduces boiler cycling and fuel consumption as compared to the baseline tests. The maximum fuel savings occurs during periods of peak heating demand. However, the magnitude of fuel savings varies depending on the control setpoints of the boiler, specifically the aquastat differential (or deadband). This paper summarizes preliminary data from this laboratory evaluation of an aftermarket boiler control system within a range of heating loads to aid in the identification of applications where it may provide the most fuel savings. [ABSTRACT FROM AUTHOR]

The objective of this paper is to investigate the performance of two different types of Solar Domestic Hot Water (SDHW) systems , one with a gas boiler as the auxiliary heating source and the other with an electric tank as the auxiliary heating source, and to investigate the contributions of different components of the systems in lowering the annual energy demand and GHG emissions for producing 225 litres (59.4 gal) per day of domestic hot water. The systems are for the twin Archetype Houses located in Vaughan, Ontario, Canada. The annual energy consumption of the gas boiler and electric tank from the experimental analysis were to be 3718.7 kWh (12.69 MBtu) and 2778 kWh (9.48 MBtu), respectively. The TRNSYS models of the two systems were also created and validated with the experimental results. Using the TRNSYS models for a typical Canadian household in Toronto, Ontario, the annual energy consumption by the gas boiler and electric backup tank were concluded to be 3636.9 kWh (12.41 MBtu) and 2681.5 kWh (9.15 MBtu), respectively. The annual thermal energy output by the flat plate and evacuated tube solar thermal collectors were found to 2010.8 kWh (6.86 MBtu) and 1390.6 kWh (4.74 MBtu), respectively. The annual heat recovery by the Drain Water Heat recovery (DWHR) units were concluded to be 792.8 kWh (2.7 MBtu). [ABSTRACT FROM AUTHOR]

Thermal comfort plays a vital role in the well being of occupants and is therefore considered very important to control. This paper compares thermal comfort of the semi-detached Archetype Sustainable Homes at the Kortright Centre in Vaughn, Ontario. This was done by following the requirements of ASHRAE Standard 55 - 2010 Thermal Environmental Conditions for Human Occupancy. These semi-detached homes have similar building envelope components however differ in HVAC technologies. The intent of House A is to demonstrate practices and technologies currently in the residential building market. The intent of House B is to demonstrate advanced technologies such as thermal mass, zoned space conditioning and in-floor heating that could be used by mass markets in the future. Results indicate House B is comfortable to a greater percent of the population. House A did not meet the draft criteria under the local thermal discomfort requirement. This was a result of the combination of drafts and lower air temperature during heating season measurements which reduced comfort levels. It is important to understand what makes a home comfortable so that improvements to energy efficiency and demand management can be realized. [ABSTRACT FROM AUTHOR]

This paper presents the application of the "Energy Balance Load" (EBL), which is developed with first law of thermodynamics, or energy conservation, in conjunction with the concepts of analytical redundancy (Shao and Claridge, 2006), as a tool for quality control of the energy consumption data patterns. The methodology has proved to be an effective data quality screening method for verification of metering sensors when heating, cooling and electricity consumption are separately recorded in a building and it is defined as the difference between the heating requirements plus the electric gains in the building and the cooling coil loads. The methodology has been used on more than one hundred buildings to verify their consumptions and to diagnostic erratic patterns. The methodology is suitable for automated application and could also be used to rehabilitate energy use data. [ABSTRACT FROM AUTHOR]

It has been known to the air moving industry for some time that duct fittings installed close to a fan's inlet or outlet can have adverse effects on the fan's performance. The magnitude of these adverse effects is generally determined through laboratory testing, and the body of knowledge is relatively small compared to the possible combinations of fan types, duct and inlet configurations, and duct fittings. The purpose of the research described in this paper was to determine the effect of a limited number of various inlet installations and product configurations on the air performance and sound of a typical forward-curved centrifugal fan. Forward-curved fans are common in heating, ventilating, and air-conditioning systems. [ABSTRACT FROM AUTHOR]

One of the main goals of ventilation is to create a favorable thermal condition inside a compartment. The efficiency of a ventilation system to achieve this goal depends on many factors such as: air flow rate, incoming air temperature, air flow pattern etc. For this purpose, there is need for a control system which can provide proper inlet conditions resulting the required output at a specific location. The main objective of this paper is to examine the possibility to control the temperature in a ventilated chamber in different spatial regions individually. Twenty two-dimensional spatially fixed and equal square cells in a small ventilated test chamber (0.70 x 0.65 x 0.4 m; 27.56" x 25.60" x 15.75") were used. Step inputs in ventilation rate and inlet air temperature are applied and temperature responses at 30 sensor locations are recorded. First order transfer function data-based models are identified for modeling the dynamic behavior of temperature in each of the 20 cells. A Proportional-Integral-Plus PIP control system is designed based on the identified models to control the temperature in each of the 20 cells individually. [ABSTRACT FROM AUTHOR]

This paper presents the experimental as well as the simulated performance studies on the transcritical CO2 heat pumps for simultaneous water cooling and heating; effects of water mass flow rates and water inlet temperatures of both evaporator and gas cooler on the cooling and heating capacities, system COP and water outlets temperatures are investigated. Study shows that both the water mass flow rate and inlet temperature have significant effect on system performances. Test results show that the effect of evaporator water mass flow rate on the system performances and water outlet temperatures is more pronounced (COP increases 0.6 for 1 kg/min) compared to the gas cooler water mass flow rate (COP increases 0.4 for 1 kg/min) and the effect of gas cooler water inlet temperature is more significant (COP decreases 0.48 for given ranges) compared to the evaporator water inlet temperature (COP increases 0.43 for given ranges). Comparisons of experimental values with simulated results show the maximum deviation of 5% for cooling capacity, 10% for heating capacity, 16% for system COP. This study offers useful guidelines for selecting appropriate water mass flow rate to obtain required system performance. [ABSTRACT FROM AUTHOR]