Energy Efficiency Buildings

As part of the UK's effort to combat climate change, deep cuts in carbon emissions will be required from existing housing over the coming decades. The viability of achieving such emission cuts for the UK social housing sector has been explored through a case study of Peabody, a housing association operating in London. Various approaches to stock refurbishment were modelled for Peabody's existing stock up to the year 2030, incorporating insulation, communal heating and micro-generation technologies. Outputs were evaluated under four future socio-economic scenarios. The results indicate that the Greater London Authority's target of a 60% carbon emission cut by 2025 can be achieved if extensive stock refurbishment is coupled with a background of wider societal efforts to reduce carbon emissions. The two key external requirements identified are a significant reduction in the carbon intensity of grid electricity and a stabilisation or reduction in householder demand for energy. A target of achieving zero net carbon emissions across Peabody stock by 2030 can only be achieved if grid electricity becomes available from entirely zerocarbon sources. These results imply that stronger action is needed from both social landlords and Government to enable deep emission cuts to be achieved in UK social housing. 2 Keywords domestic carbon emissions; existing social housing; zero carbon Acknowledgements This research has been carried out through an EPSRC-funded industrial CASE studentship, delivered through the Integration of New and Renewable Energy in Buildings (INREB) Faraday partnership, with support from Peabody. The authors wish to thank Rob Wall and Bev Allan at De Montfort University, Peter Rickaby of Rickaby Thomson Associates, and Simon Graham, Mary Popham and Nic Wedlake at Peabody for feedback on this research. Thanks also to Steven Firth at Loughborough University for the use of data from the Community Domestic Energy Model.

We derive an equation for zenith luminance as a function of turbidity and solar altitude based on analysis of large quantities of luminance and illuminance data measured in San Francisco, California, between September 1979 and August 1982. Using only average turbidity values to predict hourly zenith luminance as a function of solar altitude can produce large errors. We compare the equation derived from our data, which is valid over a wide range of turbidity and solar altitude, to other published models. We also compare the relationship between horizontal illuminance and zenith luminance from the clear sky and conclude that, when ideal clear days are compared, this relationship is similar to earlier work based on measurements in European climates. Finally, we compare our sky luminance distribution measurements to previous published luminance distributions using the diffusion indicatrix. Our results are intended to help improve daylight availability prediction techniques and define additional requirements for data collection.

A large amount of heat loss through building envelopes takes place via inhomogeneous components such as windows, doors, and thermal bridges. This loss can be approximated by measuring in lab the actual thermal transmittance of these components with the use of a hot box. The calibration and experimental procedures can be performed, taking into account three standards for calibrating hot boxes: the European EN ISO 8990; the American ASTM C1363-05; and the Russian GOST 26602.1-99. An experimental setup for testing the accuracy of these standards has recently been created at the University of Perugia; after a measurement campaign for the validation of the test rig, the differences of the approaches were evaluated. Results showed that although the EN ISO 8990 and ASTM C1363-05 are similar in terms of procedures definition, methodology of thermal transmittance calculation, and level of uncertainty, the GOST 26602.1-99 differs from the others since it adds individual measurements of the thermal characteristics of each sample component. The analysis highlighted that the ideal procedure should include the Russian method to define the thermal behavior of each component under analysis, with a contemporary validation of the global results to be performed with one of the other two approaches.

Green roofs help to regulate the urban climate not only by evapotranspiration but also because of their insulating effects leading to reduced energy demand in summer and winter. Microclimate models as ENVI-met allow to calculate effects of green roofs and their contribution to climate change adaptation. Most models are based on generalized assumptions concerning evapotranspiration, albedo, heat flux and u-value of green roofs. Building physics software as ArchiPHYSIK lacks of available data concerning green roofs. This paper provides a detailed description of seven different green roof systems (differing in thicknesses, materials and construction layers) and their insulating performance over a period of 15 months. This shall allow researchers to choose more specific data for their work and improve the accuracy of green roof simulations and energy efficiency calculations. The results show clearly, that green roofs, as "living dynamic systems" respond differently on climatic framework conditions. The calculated u-values range from 0.944 W/m 2 .K-measured for a 12 cm thick one layer green roof-to 0.299 W/m 2 .K of a 30 cm thick two layer green roof. The tested green roofs have been selected to be able to analyze the influence of different materials, construction types and thicknesses on insulation performance. Apart from construction thickness, water capacity of growing layer and drainage material, their pore volume and the application of drainage boards have been identified as relevant factors.

Like the digital pets the project is named for, the Tamagotchi Project will use aspects of the building system (lighting, HVAC, audio-visual) to deliver environmental cues (colors, temperature changes, sounds, even scents) anthropomorphizing the building. The hypothesis of the Tamagotchi Project is that a feeling of nurturance may be induced, resulting in a desire to ‘feed’ the building through appropriate energy usage. In this paper, we look at the history of environmental cues, spatial design, and human behavior. This review is preliminary to the installation of experimental equipment at up to seven sites in the United States. Hypothesis Using well-established theories of behavior, a quasi-experimental model will attempt to determine if people’s energy use in commercial buildings can be affected through the manipulation of the environment. In this paper, I discuss how environmental context stimulates activities and affects perception—in particular, color (Kuller and Mikellides, 20...

From the thermal point of view, windows represent the weak link between the internal and external ambients of a room. In cold climates, they are responsible for 10-25% of the heat lost from the heated ambient to the external atmosphere. In hot climates, the excessive solar radiation entering the internal ambient through the windows leads to increasing the cooling load of the refrigeration system. The use of absorbing gases filling the gap between glass sheets appears to be an alternative solution for thermally insulated glass windows. The other options one may incorporate filling materials such as silica aerogel or a PCM. In this work, a comparison between the thermal efficiency of two glass windows one filled with an absorbing gas and the other with a PCM and exposed to solar radiation in a hot climate is done. To model double glass window filled with infrared absorbing gases, a CW real gas model is used. A radiative convective conductive model and a radiative conductive model were investigated. Three mixtures of gases were used; a strongly absorbing gas mixture, an intermediate absorbing gas mixture and a transparent to infrared radiation mixture. To model the double glass window filled with a PCM, a relatively simple and effective radiation conduction one dimensional formulation is used. Heat transfer through the window is calculated and the total heat gain coefficients are compared and discussed.

System on programmable chip for the performance estimation of loom machine, which calculates the efficiency and meter count for weaved cloth automatically. Also it calculates the efficiency of loom machine. Previously the same was done using manual process which was not efficient. This article is intended for loom machines which are not modern.

The use of solar energy for the heating of buildings, via storage walls, has been extensively studied and several components have been developed since the Trombe works. The standard Trombe wall has two main drawbacks. During cold and cloudy winter days, it causes important heat losses and thus discomfort to the occupants. In summer it creates important and undesired inputs. These drawbacks can be eliminated by a more complex design such as the composite Trombe wall. In connection with architects such as J. Michel, we designed a massive solar wall, with an insulating panel located just behind it. A ventilated air layer exists between this panel and the wall. Vents located at the top and the bottom of the insulating panel allow air circulation and thus energy inputs to the building. A prototype was built into a test cell at Cadarache and was tested for 2 years. This allowed various climatic conditions and operation modes to be examined. We used tangential gradient type heat fluxmeters to determine the thermophysical properties of the massive wall and we quantified the heat transfers in the ventilated layer and to the building. The data obtained are now being used as input for a software to assess the performance of this improved component.

This paper deals with European TRY weather data processing for climatic indexes generation, useful for HVAC energy and cost simplified evaluation. For nine Italian locations are presented: 99 and 2)5% dry bulb temperatures, 2)5% wet bulb temperatures, heating and cooling degree days, latent enthalpy days, unitary sensible and latent loads. TRY psychrometric data were processed according to a bin method that preserves the correlation between dry bulb temperature and moisture content, and then reduced by an averaging technique. An example is worked out in order to present an engineering shorthand for energy and cost evaluation of HVAC system.

Since antiquity, man used to stock up materials and products existing in his close surroundings to build his house, which provides him shelter and comfort. Within the present work, mixtures of plaster and dune sand have been studied with the aim of valorization of locally abundant materials. The tests showed that with the addition of dune sand and the compaction, an optimal mixture (67% plaster and 33% dune sand) can be used as a carrier element for construction of up to three levels; since significant increase of the mechanical strength has been observed. The element obtained offers an acceptable thermal insulation with a decrease in the thickness of the outer wall construction. The use of this gypsum's mortar block as a carrier element in a structure not exceeding three levels, also enables a considerable savings especially in areas where sand and plaster are abundant and relatively inexpensive.

Although, the Civil Engineers are relentlessly working with the goal of enhancing the quality of human life by providing the buildings which offer comfortable, carefree and healthy life to its occupants, there are still challenges faced by them. The environmental impact of construction activities, increasing demands for resources like water and energy with their rapid depletion, global warming are the major snags till to be surmount to achieve their goal. 'Green and Energy Efficient Buildings' provide the solution to this by efficient use of the resources, reduce waste, pollution, and protect health of occupants. This paper deals with the challenges faced by the Construction Industry, while constructing the Green and Energy Efficient Buildings and discusses the possible solutions to overcome these challenges.

There has been extensive research in the field of building modelling for adaptive and, increasingly, for predictive control. The inclusion of predictive control in building energy management and control systems shifts the calculation of optimum control strategies to the future and allows the prompt evaluation of various control scenarios. The energy saving potential of CO 2 based demand controlled ventilation is well established. Although several studies have investigated the potential of incorporating CO 2 in building energy and indoor air quality management, in most cases the applications are reactive rather than predictive. Incorporating CO 2 concentration as a factor in predictive models may unlock further optimisation opportunities in controller applications, especially in buildings with highly varied occupancy, such as institutional buildings. The objective of this study is to investigate the potential of creating predictive models tailored to specific spaces in order to estimate future CO 2 concentrations. For this purpose, both measured and simulated data will be combined. The simulated data will be provided by a detailed building model, while the final identified model of CO 2 concentration will be a state space representation derived from a prediction error minimisation method. The results suggest that there is indeed potential for at least short term prediction using a very simple identification procedure.

For domestic buildings to meet current definitions of zero carbon the building fabric and services must achieve 70% reduction in energy use, taking the carbon emissions down to less than 7 Kg CO2/m2. However, there is a significant obstacle to such endeavours. The ...

This article gives a description of the typical features of construction experience and the system of heating for the indigenous people of the Chukotka Administrative District, Russia. Construction and dimensional-spatial characteristics of portable framework structures-yarangas-are described. Attention is given to the organization of the indoor space of the dwelling and traditional use of the space. The article describes the principles of heating and creating favourable climatic conditions inside the dwelling. The author gives the results of laboratory tests of the thermal shield resistance of insulation walling of a yaranga and the results of experimental studies on the indoor temperature of the air in the conditions of normal use of the structure. Experimental laboratory and field studies permitted the calculation of the theoretical thermal-technical model of a yaranga and determine the heat loss by the indoor and outdoor insulating structures. Based on the experimental data received, a theoretical calculation of heat losses of the structure is performed that proves the energy effectiveness of the two-step system of heating of a yaranga, suggesting using a similar scheme in the practice of designing modern residential settlements of the Far North.

This paper reports on the use of nanoparticles of titania (nT), superabsorbent polymer (SA) and phasechange material (PCM) in order to obtain the functionalization of mortars. Single, binary and ternary mixtures with 0-1 wt.% nT, 0-1 wt.% SA, 0-20 wt.% PCM were based on flow table measurements (∼140 mm) to estimate the individual and interactive effect between the additives. In general, the mentioned additives showed distinct behaviors, but the PCM particles predominate on most of properties and also on the performance of others additives. SA particles exhibited quite different rheological behavior if compared with other additions, due to high affinity with the water and stronger absorption levels. The PCM-containing mortars attenuate and delayed the temperature changes, while 1SA particles resulted in higher hygroscopic capacity. Moreover, the photocatalytic degradation of NO x reached 40-45%. In addition, the moisture buffering value of 1SA, 1nT and 20PCM mortars were classified as good according to the Nordtest method.

A complete review on scale model testing for buildings, considering a wide range of methodologies and new manufacturing techniques, in areas such as statics and dynamics, acoustics, lighting, aerodynamics and thermodynamics for energy efficiency is presented. On the one hand, scale model testing for buildings require different considerations and techniques and are usually focused on one specific physical field contributing to the information scattering. On the other hand, they are sometimes too general, theoretical or unpractical. Although commercial computer simulations are first option among professionals, they necessarily simplify complex phenomena and ignore, among other aspects, size effects and latest findings in fractals. The potential of complementary experiments using new manufactured scale models for buildings is raising, however, it is still missing a practical overview through different physical fields specifically for buildings with these considerations. This review gives a wide perspective and unified scope on uses and possibilities of scale model testing for buildings, from the traditional configurations of Leon Battiste Alberti to new possibilities applying complex physics and new techniques of 3D-modelling.

The world has witnessed a significant population shift to urban areas over the past few decades. Urban areas account for about two-thirds of the world's total primary energy consumption, of which the urban building sector constitutes a significant proportion approximately 40%. Stakeholders such as urban planners and policy makers face substantial challenges when targeting sustainable energy and climate goals related to the buildings' sector, i.e. to reduce energy use and associated emissions. Urban energy modeling is one possible solution that leverages limited resources to estimate building energy use and support appropriate policy formation. Over the past few years, there have been only a few review studies on urban building energy modeling approaches. These studies lack an in-depth discussion of the challenges and future research opportunities related to data-driven, reduced-order, and simulation-based modeling methods. This paper proposes Strengths, Weaknesses, Opportunities, and Threats (SWOT) analysis of approaches, methods and tools used for urban building energy modeling. Furthermore, this paper proposes a generalized framework based on existing literature for different urban energy modeling methods. The aim of this study is to assist urban planners and energy policymakers when choosing appropriate methods to develop and implement in-depth sustainable building energy planning and analysis projects based on limited available resources.

As a result of the depletion of natural resources, destruction of green areas, loss of ecosystem and consequent shrinkage of habitable areas, the concept of "sustainability" has become an important parameter at all stages in architectural discipline as in all fields. However, in some cases this notion has started to transform into an advertising tool developed to feed consumption due to its structure being open to interpretation, its current value and its lack of adequate supervision. Sustainability has three aspects that are economic, social and physical. Apart from the successful architectural designs that take all the values of sustainability into account, the concept has also been used as a popular culture item that enables the projects to come forward and be preferred by people. In this study, the phenomenon of "greenwashing" was examined and five architectural projects from Turkey with the claim of sustainability were evaluated within the criteria of three sustainability scopes.

This paper introduces various electrical and thermal energy generation, consumption, and storage components in solar powered low-energy buildings. Dynamic management of such energy components is essential given the stochastic solar resources. Emphasis is put on power electronic HVAC (heating, ventilation, and airconditioning) drives, which can act as an effective electric swing bus to mitigate solar power variability. In doing so, grid power flows become substantially more constant, reducing the need for fast grid resources or dedicated energy storage such as batteries. The concept is equivalent to using building thermal energy as virtual dynamic storage in support of power grid operation. The paper defines a bandwidth over which such HVAC drives can operate. A practical band-pass filter is realized that provides 1) lower frequency bounds such that the building maintains consistent room temperature via the HVAC system as demonstrated by a thermal modeling study, and 2) upper frequency bounds that ensure commanded HVAC fan speeds do not update arbitrarily fast. The latter primarily avoids acoustic discomfort to users. The combination is illustrated by experimental results based on various update rates of a variable frequency fan drive over a sample of actual stochastic solar data. Building electrical and thermal energy systems modeling by MATLAB is addressed throughout the paper, including solar and HVAC systems as well as batteries and water tanks. Index Terms—Low-energy buildings, frequency domain analysis, grid-level energy storage, HVAC systems, solar energy, thermal storage, power electronic drives, complex system energy management

Several studies have shown that the actual energy performance of buildings can differ significantly from its designed value. An important part of this performance is constituted by the building fabric's thermal performance. A common method to evaluate the latter for an actual building is the co-heating test. The co-heating test comprises a quasi-stationary heating experiment followed by linear regression analysis of aggregated building performance data. This paper reviews related research work and cristallises the current state-of-the-art. The physical phenomena working behind the scenes of the generally assumed simplified heat balance are discussed. Statistical constraints generally prevent these from being uncovered fully during the analysis. Multiple linear regression is proposed as the most sensible method to analyse co-heating measurement data. A novel way to visualise such analysis, deduce building performance data graphically and compare different co-heating test results is presented.

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Field observations were carried out to determine the influence of a park on the urban summer climate in the nearby areas. The possibilities of reduction in air conditioning energy were investigated. Air temperature, relative humidity and other meteorological factors were measured at many locations inside a park and in the surrounding areas in the Tama New Town, a city in the west of the Tokyo Metropolitan Area, Japan. The observations indicated that vegetation could significantly alter the climate in the town. At noon, the highest temperature of the ground surface of the grass field in the park was 40.3 °C, which was 19 °C lower than that of the asphalt surface or 15 °C lower than that of the concrete surface in the parking or commercial areas. At the same time, air temperature measured at 1.2 m above the ground at the grass field inside the park was more than 2 °C lower than that measured at the same height in the surrounding commercial and parking areas. Soon after sunset, the temperature of the ground surface at the grass field in the park became lower than that of the air, and the park became a cool island whereas paved asphalt or concrete surfaces in the town remained hotter than the overlying air even late at night. With a size of about 0.6 km2, at noon, the park can reduce by up to 1.5 °C the air temperature in a busy commercial area 1 km downwind. This can lead to a significant decrease of in air conditioning energy in the commercial area.

This study directs attention towards the New Cairo community, which is one of the new urban settlements that have been developed around Cairo, Egypt. People recently have tended to install or extend mechanical cooling equipment in their dwellings in order to overcome the problem of thermal discomfort from overheating. Although the mechanical cooling significantly raises utilities bills, it is still the preferred choice for the majority of the residents. The lack of awareness about the advantages of Passive Cooling Techniques (PCT), in addition to uncertain about their costs and effectiveness, has made PCT unpopular options for both designers and owners. This study investigates the costs and benefits of two PCT, which include the influence of the thermal transmittance of the walls (U-value), and the attachment of solar shading devices. The Whole Life Cycle Costing (WLCC) evaluation method is used to estimate the payback period of applying the PCT. The PCT were simulated using the dyn...

Low energy buildings use less than 50 % of the energy used in typical buildings. Such energy efficient buildings can only be achieved by applying unconventional approaches. However, the applicability of the unconventional strategies and techniques is challenging. This proposal presents an innovative idea that can be applied to overcome barriers to implementation of one of these unconventional techniques that used to maximize the utilization of daylighting within buildings.
Daylight guidance systems (DGS) deliver daylight into windowless and remote parts of buildings via light ducts or fiber optics. DGS that based on light duct to channel daylight are relatively economical, more likely to maintain daylight characteristics, and capable of delivering both direct and diffused daylight. However, they still lack widespread use due to installation difficulty. They use light ducts that occupy significant spaces to distribute daylight. The integration of DGS light ducts and HVAC ducts emerges as a novel and promising solution. The integrated dual ducting system has the potential to maximize the utilization of daylighting, reduce costs and avoid conflicts between building systems.
The widely used HVAC systems uses duct networks already integrated with the other building systems. The HVAC ducts are capable of reaching most spaces, and are of comparable size to light ducts. Thus, they are a prime target for the development of dual ducts; a single duct to transport and distribute both air and light.
The proposed system is very practical and benefit from the available facilities to produce a new product and propose a new design approach. Cooperation between architect/lighting designer and HVAC designer can be made to convert conventional ducts network design and material into the dual ducting system. There is no other product on the market that is used to deliver both air and daylight, and no other system has been designed or developed to provide this service.

A summary of the evaluation of an air flow and contaminant model as part of the IEA-ECBCS Annex 23 `Multizone Airflow Modelling' is presented. Evaluation, rather validation, is the goal. The most important points of the cases analyzed during this project are presented and commented from the point of view of analytical evaluation, comparison with experimental data and user sensitivity. The conclusion addresses the need for user-friendly tools and guidelines for the analysis of simulation output.

While it is possible to check the energy performance of a given building by means of several available methods, the inverse problem of determining the optimum configuration given a desired performance is more difficult to solve. In the Mediterranean region this problem is more complex due to the following two reasons: the air-conditioning load is as important as the heating load, and the energy needs depend on a high number of architectural parameters which have different, even contradictory, effects on summer and winter loads. In this paper we present an optimization algorithm that couples pseudo-random optimization techniques, the genetic algorithms (GA), with a simplified tool for building thermal evaluation (CHEOPS) for the purpose of minimizing the energy consumption of Mediterranean buildings. Since increasing the energy performance usually requires the use of special devices resulting in a high construction cost, we also propose to use GA for the purpose of economical optimization. #

Current difficulties surrounding air conditioning systems involve an increase in input air aimed at improving indoor air quality (IAQ), the financial costs arising from energy consumption and external environmental impact, linked to the greenhouse effect (GWP) and the destruction of the ozone layer (ODP). One alternative technique which offers an adequate combination of IAQ and acceptable energy saving is the

The building sector in Europe is responsible for an estimated 40% of the total energy consumption and 10% of the total CO2 emissions. Given that new buildings represent only about 1% of the housing stock annually, it is estimated that more than 80% of the existing buildings will still exist in 2020. Therefore, the energy efficient renovation of the existing housing stock is imperative in order to reduce the building energy consumption. It is for this reason that the European Union ranked the improvement of the energy performance of the old building stock, as a high priority in its research agenda. Following Europe's 20:20:20 objective, this case study investigates refurbishment scenarios in order to achieve Nearly Zero Energy houses, in Cyprus. The research focuses on the Single Family House typology, as classified in previous studies for Cyprus, in the framework of the IEE, EU project EPISCOPE and specifically on retrofitting an old house that was built before 1980. The aim is to upgrade it into a Nearly Zero Energy Building (nZEB) with the implementation of the national energy performance requirements, as drafted by the Ministry of Energy, Commerce, Industry and Tourism (MECIT). Following the EPISCOPE project methodology, a representative Single Family House from the corresponding residential building typology in Cyprus was chosen and modeled using the iSBEMcy tool. This is the official governmental software in Cyprus used for issuing Energy Performance Certificates (EPC), for the categorization of the energy class of the building and the calculation of the CO2 emissions according to the European Directives 2002/91/EC and 2010/31/EC. The study investigates whether it is possible for an old Single Family House to reach the nZEB standards and identifies the lurking obstacles and challenges, through building simulations. To this end, various refurbishment scenarios were developed, with the implementation of strategies aiming at fulfilling the MECIT requirements. Through analysis of the results, the efficiency of each strategy and technique employed towards minimising the energy consumption and the greenhouse gas emissions was

The paper discusses two main points; first is the validity of steady state analysis in assessing buildings’ heating and cooling loads, as well as the internal air and surface temperatures (TAIR, TSI) using UNI TS 11300-1:2008 compared to TRNSYS dynamic simulation software. The second aim is to understand how internal insulation affects the building envelope thermal inertia. Insulation is important to conserve heat in the heating season; however, it may contribute to space overheating in the summer. Thermal capacity is important in increasing human comfort in the space, limiting overheating in summer and managing peak temperatures due to internal or solar gains. Inside insulation can alter the dynamic behaviour of the existing envelope, and the aim is to understand the consequences of this intervention. The work presents an analysis of different internal envelope retrofitting solution, and deal with the climate of Milan and Palermo cities in Italy. The results show that steady state ...

There is a significant potential for energy efficiency improvements in the residential buildings in Kazakhstan. The analysis of energy audits confirmed this statement: heat transfer coefficient of walls is much higher than in European countries with similar climates. In consequence, households consumption of energy in Kazakhstan per square meter of area is nearly three times higher than in Europe. Energy efficiency options with payback period of less than 10 years may contribute in average to the 10% reduction of energy consumption. While all energy efficiency options may contribute in average to 27% reduction of total energy consumption by building. Energy efficiency options with low investment costs and relatively high economic savings are pipe insulation and energy efficient lighting. Whereas recovery of insulation of external walls and basement, energy monitoring as well as replacement of windows and doors in communal entrance hallways are measures with low investment costs and relatively moderate economic savings. There are energy efficiency options with very high payback period – more than 48 years-such as insulation of walls, automated heat supply station, insulation of roofs as well as replacement of windows. These measures are unlikely to be implemented by homeowners themselves, without supporting mechanisms from the Government.

Simplified correlation methods are powerful :ools to compare both the energy performance of buildings and the efficiency of different HVAC control systems. For buildings in which both heating and cooling loads contribute to the energy consumption, widely used methods. like the energy signature models, are not appropriate. since they cannot simultaneously handle both heating and cooling aspects. This paper proposes a new correlation method to overcome this difficulty. The 'Eta method' deals with internal gains, as well as solar gains, and can be used to calculate a utilization factor for free gains in the heating and cooling periods. Two examples to illustrate the method are given. The first one is a passive solar office room, on which different blind controllers were tested by simulation. The second example is a non-residential building in which two HVAC controllers were carefully monitored. 0 1998 Elsevier Science S.A.

A meta-analysis of seasonal performance for ground to water and air to water heat pumps based on eight European trials for over 600 installations from five countries provides thirteen different descriptors of performance. Seven of these trials have previously been publish but no overview of their results has been attempted in terms of system boundary analysis. Trial boundaries are rationalised to four values of seasonal performance providing the opportunity to reassess the UK EST heat pump trial results and identify two boundary conditions directly relevant to the interpretation of the Renewable Energy Sources Directive. What is apparent is the wide range in performance at all boundaries and in all trials indicating that heat pumps are sensitive to design and installation practice. The overarching theme of the paper is the need for a unified framework for reporting heat pump performance and its applicability to the reanalysis of existing data. The task of building such a framework has proved beyond the present author, but the work presented here represents an attempt to scope the potential value and combination of analytical and practical difficulties that would need to be faced by those undertaking such a task.

a b s t r a c t HVAC plant designers and energy auditors often face the problem to calculate the performance of heat pumps under various boundary conditions. In this paper a model aimed at that purpose is presented. In particular, the model presented is aimed at the simulation of vapor compression based heat pumps or chillers driven by volumetric compressors. It is a numerical model tracing a reference thermodynamic inverse cycle consistent with the specific heat pump or chiller under the requested boundary conditions. The input data necessary are few and easy-to-find, especially if compared with the other simulation models proposed in literature. The proposed simplified model makes it possible to use catalog data in order to get reliable results. Even if the amount of input data required is low, the numerical model showed a good accuracy (within 10%) contrasted against performance declared by manufacturers. Moreover, the model has low sensitivity to user assumptions so it is valid also for the prediction of the performance in old HVAC plants. Moreover, this numerical model is fast and suitable for integration within building energy simulation tools. The present model does not take into account air dehumidification at the evaporator nor defrost cycles, whose implementation is currently in progress.