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Much research has been focused on maintaining stable humidity conditions in buildings housing heritage collections while reducing energy use. Moisture buffering by collections themselves can have a marked effect on the stabilisation of relative humidity (RH), the key parameter for preservation. Modelling of moisture transport using COMSOL Multiphysics was applied to transform three-dimensional paper and wooden objects into their one-dimensional representations, without changing the moisture uptake and release characteristics. The results were coupled to the modelling of indoor microclimate and energy consumption in collection storage spaces with the use of WUFI ® Plus software. The study revealed the crucial impact of air exchange rate of the building on the stability of indoor RH and the humidification and dehumidification loads required to maintain it. In the adequately air-tight library store, a sizeable paper collection was found to reduce the RH fluctuations from ±9% to ±6% around the yearly average and the energy consumption due to the humidification and dehumidification load by 38% when compared with the empty space, for a high-quality climate control scenario. In turn, a wooden collection, occupying a realistic fraction of a museum store was not large enough to significantly narrow down the RH variations and reduce the energy consumption.

One of the most important factors in the thermal behavior of exterior walls is the thermal conductivity of the clay in their bricks. The higher the percentage of lightening additives incorporated, the better the thermal behavior of the bricks. But as their thermal characteristics are improved the mechanical properties of bricks deteriorate. The goal is to study the influence of paper pulp as a lightening additive on the thermal and mechanical properties of the fired clay, and to improve the thermal properties as far as possible without the mechanical properties falling below the required levels. This involved the preparation of test specimens that were then subjected to the corresponding assays of thermal conductivity and mechanical strength. It is found that around 15% of paper pulp can be added without the brick's mechanical properties ceasing to comply with current legislation. This amount of paper pulp has improved conductivity properties by 39.69% compared to the clay without additives, recording a minimum conductivity value at 10 °C of 0.45 W/m-K. This decrease in the conductivity of the clay results in a 16% improvement in equivalent thermal transmittance for brick walls made in the same way.

Heat recovery from wastewater is of considerable significance to energy conservation and environmental protection. However, all types of wastewater contain suspended foulant. This leads to fouling on heat exchanger surfaces, resulting in low heat transfer efficiency and blocking heat exchanger. Therefore, the use of wastewater source heat pump (WWSHP) is considerably restricted. In order to avoid the fouling on wastewater heat exchanger (WWHEX) to achieve a better performance, a novel WWSHP system was proposed. The detailed structure and experimental performance evaluation of the operating performances of the novel WWSHP system are described in this paper. The core of this novel WWSHP system was a wastewater tower where circulating air extracted heat from wastewater through the evaporation of water, while the foulant in wastewater would stay. An experimental set-up for the novel WWSHP was established and five experimental cases were organized. In the first four cases, the effects of the variations in key system operating parameters on the operating performances of the novel WWSHP system were experimentally examined. In the fifth case, the overall operating performances of the experimental setup when recovering heat from waste bath water at 29 °C at a preset hot water temperature of 45 °C were experimentally examined. Within the wastewater tower, the main heat transfer process was via latent heat through the evaporation of water, accounting for 72.1% of the total heat transfer exchange. The results of cases 1–4 suggested that with an increase in wastewater temperature, the percentage share of latent heat exchange was also increased. However, the increases in both wastewater flowrate and circulating air flowrate had little effect on the percentage of latent heat exchange in the total heat transfer of the wastewater tower. The novel WWSHP system with the wastewater tower worked well at wastewater temperature of 8 °C, with its COPunit of 2.97 and a COPsys of 2.0 for water heating. Increasing wastewater flowrate from 1.29 m3/h to 1.77 m3/h could help improve the heat transfer rate of the wastewater tower by 4.4% and the COPsys by 2.5%, respectively. On the other hand, the experimental results for case 5 suggested that at wastewater temperature of 29 °C and a preset hot water temperature of 45 °C, the average COPunit was 4.99 and the average COPsys was 3.43, both being higher than those of conventional WWSHPs.

The apparent thermal conductivity of several insulation materials was measured over a range of temperatures. A newly developed multilayer reflective insulation system called Mirrorpanel was tested against existing products. Mirrorpanel samples were prepared using layers of aluminum foil (emissivity of 0.11) and coated paper (emissivity of 0.52) separated by air spaces of approximately 5 mm, with fiberboard structural spacers. Steady-state heat flux was measured in the laboratory for 500 mm × 500 mm samples including several Mirrorpanel configurations as well as expanded polystyrene and polyisocyanurate foam insulations. The mean temperature ranged between 0 °C and 35 °C with a temperature difference across the sample of 10 °C. For all insulation materials, the apparent thermal conductivity increased linearly with temperature above 5 °C, and the slope was steeper for the Mirrorpanel samples than the foam insulations. The apparent thermal conductivity of the Mirrorpanel made from aluminum foil was greater than that of polyisocyanurate but less than that of expanded polystyrene. The significant difference of thermal conductivity of lower and higher emissivity reflecting layers highlighted the importance of this parameter in thermal insulation. The steep temperature dependence of the Mirrorpanel should be considered during design of the building envelope for summer and winter conditions.

Straw bale construction can be utilised to deliver energy efficient and low carbon buildings, however there are concerns over the durability of straw. The water sorption property is a critical factor in the degradation behaviour of straw and other lignocellulosic materials. Typically, either wheat or rice straw is utilised for bale construction, however, this variation is not considered. This paper presents the sorption property of wheat and rice straw and the micro-structure that affect the sorption property. Although the surface and cross-sectional structure of the two straw species are different at micro scale, the sorption isotherms were not significantly different. This study on the water sorption property of rice and wheat straw allows for the assessment of durability within a wall construction. This impact of this research will be the growth in low carbon energy efficient straw bale construction with confidence over its long term durability characteristics.

The results of comparative tests of thermal insulating materials on the basis of various agricultural wastes are presented. Rye straw, barley straw, wheat straw, oats straw, rice straw, flax boon and rice husk were used in the experimental program along with three types of binders (liquid glass, emulsion of PVA and latex). Plates prepared with rye straw and flax boon fibers and liquid glass as a binder have the best physical and mechanical characteristics due to the formation of the optimal composite structure of the material from two fibers of different sizes and shapes. The electronic microscopy of rye and flax stems made it possible to establish the presence of outer and inner parts in the structure, which affect the thermal and strength characteristics. Results show that plates made from rye straw and flax boon have lower moisture absorption unlike the rye straw based ones. The results of full-scale tests with a ventilated thermal insulation system confirm the effective operation of rye straw and flax boon plates. The testing program carried out indicates the possibility of using an environmentally friendly straw-flax boon plates for thermal insulating buildings in the cold period and thereby reducing carbon dioxide emissions into the atmosphere. info:eu-repo/semantics/publishedVersion

Expert guidance in the UK suggests a limit to temperatures in bedrooms to of 26 °C or less to avoid overheating. This short paper looks at the temperatures in bedrooms and uses data from comfort surveys combined with models which link comfort to the thermal environment. Evidence is given that people sleep comfortably where temperatures are 29–31 °C in their personal space within the bed and they use bedclothes to allow them to attain these temperatures. The effect of the use of a mattress and the adaptive opportunities afforded by the bedclothes and sleepwear are briefly explored as are methods used in hot climates to offset high bedroom temperatures.

The excess flow of water increases the energy consumption of water pumps in the chilled water systems of air-conditioning units. This paper proposes a strategy to control the chilled water flow rate of a fan coil unit (FCU) using a control valve. A physical simulation test bench was built to verify valve control and energy-saving effects. Results showed that the control valve could effectively regulate the flow rate of chilled water, improve the temperature difference (delta-T) between supply and return water, and reduce the energy consumption of the chilled water pump. With a supply water temperature of 7 C and low (325 m3⋅h−1), medium (500 m3⋅h−1), and high (600 m3⋅h−1) FCU air velocity levels, the average delta-T values were 4.79 °C, 4.39 °C, and 4.97 °C, respectively, and the energy consumption of the chilled water pump decreased by 12.20%, 11.31%, and 10.66%, respectively. With medium air velocity and supply water temperatures of 7 °C, 8 °C, and 9 °C, the average delta-T between supply and return water was 4.39 °C, 3.56 °C, and 3.33 °C, respectively, and the energy consumption of the chilled water pump decreased by 11.31%, 5.10%, and 7.80%, respectively. These research results provide useful insights in relation to the problem of excess chilled water flow identified above.

A laboratory study was conducted to test the performance of non-thermal plasma air purifiers on its removal effectiveness of two haloanisoles – 2,4,6-trichloroanisole (TCA) and 2,4,6-Tribromoanisole (TBA). TCA and TBA are the two major compounds found in wine cellars that can contaminate wine to produce unpalatable mouldy and musty tastes. The test was first conducted in a climate chamber. The plasma air purifier was installed in a test rig developed for the testing and challenged by airflow with certain concentrations of TCA and TBA. Air samples upstream and downstream of the air purifier was collected by Tenax tubes and the concentration of TCA and TBA were analyzed by thermal desorption GC–MS. The results showed that the plasma air purifier was effective on removing TCA and TBA with a single pass efficiency of better than 82%. The effect was further validated in a wine cellar under a realistic condition. The concentrations of TCA and TBA in the wine cellar decreased 94% and 50% respectively after running two plasma air purifiers for 5 days. The non-thermal plasma air purification technology may be used in wine cellar to remove the two airborne contaminants and prevent the wine from being contaminated during storage.

This paper reports a study on thermal and sound insulation samples developed from waste wool and recycled polyester fibers (RPET) for building industry applications. Waste wool fiber is a potential source of raw material for thermal and sound insulation applications, but its quantities are limited. In order to overcome the above problems, waste wool fibers were mixed with RPET fibers in 50/50 proportions in the form of a two layer mat. Another set of three samples from 100% waste wool and 100% RPET fibers were also prepared. All samples were tested for thermal insulation, acoustic, moisture absorption and fire properties. Also, behavior of the samples under high humidity conditions was evaluated. An extensive biodegradability study was conducted to analyze the conversion of organic carbon into carbon dioxide by composting method for 50 days. Two layer 50% waste wool and 50% RPET mat provided the best insulation, acoustic, moisture absorption and fire properties. The RPET/waste wool mats were absorbing more than 70% incident noise in the frequency range of 50–5700 Hz. The RPET/waste wool mats have adequate moisture resistance at high humidity conditions without affecting the insulation and acoustic properties. 65–70% biodegradation was achieved for wool/RPET mats for 50 days composting period.

The process of olive oil extraction produces olive stone, a residue which cause considerable problems of disposal. This paper proposes and analyzes an original use of olive stone in order to improve the heat insulation performances of cement lime mortar and reduce its final density. To this purpose, the paper illustrates a set of small-scale tests, which were conducted on specimens of cement lime mortar mixed with different percentages of olive stone, in compliance with the protocols ISO. These tests allowed to evaluate the relations between thermal conductance, density and water absorption per each percentage of olive stone. It was observed that adding 70% of dry weight of olive stone allowed to reduce the average thermal conductance of cement lime mortar by over 76% and its density by around 30%. Furthermore, tests highlighted that the decrease in thermal conductance, which was related to the increase in the percentage of added olive stone, is greater than the decrease in density. In order for the tests to be carried out, a prototype of portable measuring system was developed, which was based on the measurement of heat flow and allowed to obtain average thermal conductance values with average error below 10%.

This paper deals with numerical methods for predicting air flow patterns in large industrial halls. Some major findings of the investigation of the airflow patterns in paper machine hall of Umka Cardboard Mill are presented in the paper. The main reason for the interest in this problem is to find optimal locations for extract air intake connections of the ventilation system connected to the exhausted air waste heat utilization. Previous studies have shown that the amount of heat released from the cardboard machine to the surrounding air in the hall and extracted by the series of ceiling mount axial fans was almost 30% of the total waste heat from the paper machine's drying section. These results have indicated the need for the waste heat utilization, but also for the optimization of the ventilation system. CFD simulation for predicting of air flow patterns was applied. The accuracy of the simulation was evaluated by comparing its results with the results of field measurements. Simulation results served well for qualitative analysis, gave better insight in general air movements inside the hall and indicated the extract air intake locations. By utilizing the waste heat from proposed optimal locations, fuel savings of 5% and reduction of 1140 t/year in CO2 emissions can be achieved.

The building sector, one of the fastest growing in terms of energy consumption, accounts for over 40% of final energy, a figure which is growing. Building energy legislation at EU level is found in EU Directive 93/73/CEE [Directive 93/73/EEC of the Council of 13 September 1993 on the Limitation of the Carbon Dioxide Emissions through the Improvement of Energy Efficiency (SAVE) 1993], EU directive 2002/91/CE called Energy Performance of Buildings Directive EPBD [Directive 2002/91/EC of the European Parliament and of the Council of 16 December 2002 on the Energy Performance of Buildings] and the EU Green Paper [Commission of the European Committees, Green Paper, Towards an European Strategy for the Security of Energy Supply, Brussels, 2000]. This give a clear view of the need and priority that the EU has for reducing energy consumption in the building sector, both for furthering in compliance of international agreements (Kyoto protocol and forthcoming commitments) as well as for reducing its energy dependency, and hence for leading its development towards sustainability. The implementation of the EPBD has as its primary aim the establishment and application of energy certification programs. The aim of energy certification programs is to guarantee energy saving and to reduce CO2 emission as a consequence of the EU commitment to comply with the Kyoto protocol. Obtaining energy effectiveness labelling means the achievement of energy quality, allowing a decrease in CO2 kilograms emitted from lighting, heating and cooling buildings without any loss in terms of comfort. This work proposes a new methodology called Building Energy Analysis (BEA) that allows implementation of EPBD on energy certification of buildings. In this paper we analyse the different steps of BEA methodology (heat and cooling load, energy demand, energy consumption and CO2 emission). The program ends with energy labelling of the building. In addition, we present a practical study of a small health centre that is analyzed with BEA methodology and we compare it with other energy simulation programs like Hourly Analysis Program (HAP) and PowerDOE. The results of energy labelling are very similar for both simulation programs.

The hygroscopicity of a wooden material or the ability to absorb, store and release moisture helps to naturally regulate the indoor climate by dampening humidity variations and avoiding extremes. This phenomenon, known as moisture buffering, is an energy-efficient way of moderating moisture levels in a living space, improving air quality, and influencing the health and comfort of the occupants. This work focused on developing a surface treatment that preserves the natural ability of timber to buffer moisture vapor whilst increasing the resistance to liquid water. For this purpose we suggest a method based on a natural non-continuous coating of hydrophobic Carnauba wax particles. The coating was compared, in terms of water repellency and moisture buffering efficiency, to a continuous wax film and conventional coating methods like lacquer and linseed oil. The resistance of the surfaces to liquid water was studied by Contact Angle measurement. Moisture Buffering experiments were conducted by exposing the surfaces to cyclic changes in relative humidity. It was found that coating with wax particles resulted in more hydrophobic surfaces with enhanced moisture buffering ability, whilst the rest of the coatings examined either reduced moisture buffering drastically (wax film, lacquer) or were not sufficiently hydrophobic (linseed oil).

This study investigated the effect of exhaust hood during cooking case-study dishes of Eight Cuisines of China. Parameters were measured of hood idle or working mode included the continuous measurements of air temperature, air relative humidity and generations of CO, CO 2 and TVOC of the breathing zone. Different from former researchers, we found the cooking techniques are not the reason that causes serious pollution. The emissions of CO and CO 2 not only were related to the cooking time, but also occurred largely as a result of the burning of the gas; however, the generation of TVOC attributed in large part to using the seasonings, ingredients and the behavior of marinating. The maximum increase of TVOC concentration during cooking dishes with cooking wine was at least 526.7–543% higher than the others. Besides, the behavior of marinating would cause at least 80–556.3% increase. Compared to hood idle mode, the decrement of maximum increases of temperature, CO 2 and TVOC concentrations were 7–50.29%, 6.6–379.5% and 136.6–4211.6% respectively in hood working mode. The situation became very complicated for relative humidity and CO concentration. Even with an exhaust hood, there was still a significant high value of contaminant levels in the breathing zone, especially in the beginning phase of the cooking process (200 s). The values of test parameters finally reached a stable value after a certain period of time. This time of hood idle mode was almost the double of the hood working mode.

A solar drying system was designed, constructed and tested for drying of seaweed. Seaweed is a potential source of renewable energy, and it can be converted into energy such as biofuel oil, biodiesel and gas. Red seaweed was dried to the final moisture content of 10% from 90% w.b in 15 h. Drying kinetics of red seaweed were investigated and obtained. The nonlinear regression procedure was used to fit three different drying models. The Page's model clearly showed a better fit to the experimental data between Newton's model and Henderson and Pabis model. The Page's model was resulted in the highest value of R2 and lowest values of MBE and RMSE. At average solar radiation of about 500 W/m2 and air flow rate 0.05 kg/s, the collector, drying system and pick-up efficiencies were found about 35, 27 and 95%, respectively. This study was performed with energy analysis and exergy analyses of the solar drying process of red seaweed. The specific energy consumption (SEC) of 2.62 kWh/kg was obtained. Moreover, the exergy efficiency of solar drying ranged from 1% to 93%, with an average of 30%. The values of improvement potential were found to be in the range of 0.3 and 630 W, with an average of 247 W.

Carbon nanomaterials can be applied to the manufacture of wood-based building materials in the solid state and paint/adhesives in the liquid state to reduce emissions of formaldehyde and volatile organic compounds (VOCs). Among carbon nanomaterials, graphite is a layered material consisting of one-atom-thick sheets of carbon. The carbon atoms are bonded covalently in a hexagonal arrangement within the layer and these layers are bonded to each other by weak van der Waals forces. The α-spacing between the carbon layers is 0.335 nm. Since the van der Waals forces are relatively weak, it is possible for a wide range of atoms, molecules and ions to intercalate between graphite layers to form the graphite intercalation compounds (GICs). Expandable graphite consisting of natural graphite flake intercalated with acid, can be expanded up to hundreds of times its initial volume at high temperature, resulting in separation of the graphene sheets at the nanoscopic level along the c axis of graphene layers. Because expanded graphite is a porous carbon material, it can be applied to building materials such as wood flooring and wood-based composite after surface treatment for multi-functional building materials. To support its application to building materials, we examined the adsorption performance of graphite using a thermal extractor (TE) and 20 L small chamber. In addition, we also conducted Fourier transform infrared spectroscopy (FT-IR) analysis to confirm the variation in accordance with the modification process of graphite.

More than sixty environmental product declarations of insulation materials (glass wool, mineral wool, expanded polystyrene, extruded polystyrene, polyurethane, foam glass and cellulose) have been examined and the published information for global warming potential (GWP) and for embodied energy (EE) has been analysed and is presented. A peer-review literature survey of the data for GWP and EE associated with the different insulation products is also included. The data for GWP (kg carbon dioxide equivalents) and EE (megajoules) is reported in terms of product mass or as a functional unit (FU) (1 m2 of insulation with R = 1 m2 K/W). Data for some classes of insulation material (such as glass wool) exhibit a relatively narrow range of values when reported in terms of weight of product or as a functional unit. Other classes of insulation material exhibit much wider distributions of values (e.g., expanded polystyrene). When reported per weight of product, the hydrocarbon-based insulation materials exhibit higher GWP and EE values compared to inorganic or cellulosic equivalents. However, when compared on an FU basis this distinction is no longer apparent and some of the cellulosic based materials (obtained by refining of wood chips) show some of the highest EE values. The relationship between the EE and GWP per kg of insulation product has also been determined as being 15.8 MJ per kg CO2 equivalents.

Recent simulation-based studies have indicated that load shifting using Economic Model Predictive Control (E-MPC) of radiators for residential space heating can be utilized for demand response purposes in energy systems. However, there is a lack of studies on whether this load shift potential can be realized in real, inhabited buildings. This paper reports on a field experiment aiming at realizing load shifting of space heating in a single-family house with a hydronic radiator system connected to the local district heating. Radiators in a limited number of ‘active’ rooms were controlled using set-point schedules mimicking the typical behavior of E-MPC. The results indicate that it was possible to load shift heating consumption in the ‘active’ rooms but that the load shift for the building as a whole was limited due to the hydronics of the radiator system. The paper also reports on the several practical issues encountered during the experiments – issues that in different ways are barriers to the practical realization of demand response from E-MPC of hydronic space heating systems.

On-site measurement of the actual thermal performance of a building envelope could considerably benefit to the building sector by securing an effective performance of newly built or retrofitted buildings. Current methods to estimate the Heat Transfer Coefficient, for example, suffer however from either excessive equipment downtime and therefore large costs, or fail to achieve a reasonable accuracy. This paper aims therefore at developing and assessing an original 24-hour perturbation method for estimating the whole-building thermal resistance. Based on a binary heating signal, the proposed method exploits the data collected with stochastic RC models.The paper first presents a numerical comparison of 398 binary signals along with variable initial indoor temperatures to bring out common characteristics of signals that achieve highly accurate estimations of the thermal resistance. An experimental campaign in a highly insulated wooden-framed house then implemented one particular signal and assessed its reproducibility under variable weather conditions. The paper shows that the proposed 24-hour method indeed achieves a highly accurate estimation when performed in cold weather. In midseason conditions, the method shows a better robustness from 30- to 36-hour measurements. The results invite to further investigate other building types in variable weather conditions to validate the proposed method.

This paper presents a simulation study of an active energy storage device intended to enhance building operation. This device –which is designed for installation in the ceiling plenum of an office, a mechanical room or in other convenient locations– consists of an arrangement of several panels of a phase-change material. It may be charged or discharged as required with an air stream passing between the panels, thus operating as a PCM-air heat exchanger (PCM-HX). The first part of the paper focuses on the design of the PCM-HX. Several design configurations are evaluated; investigated parameters include the PCM-HX dimensions, the number of air channels and airflow rates. The paper also includes an experimental validation of the PCM model. Performance criteria that were considered in the parametric study include the amount of stored heat, the time needed to charge/discharge the PCM storage and the overall energy density of the device. The second part of the paper evaluates different control strategies aimed at reducing peak demand and the size of HVAC system. The impact on peak load of a linear ramp for the temperature setpoint is investigated: it was found that a two hour linear ramp in temperature setpoint –together with a PCM-HX configuration with six air channels– can reduce the peak heating load by 41% as compared to a benchmark case without the PCM-HX.

The article presents long-term results of experimental tests of a hybrid installation (HI) consisting of four heating devices, three of which use renewable energy sources (RES). The HI is operating in a residential and retail building located near Krakow, in southern Poland. There is little experience with the operation of such installations, therefore, the purpose of this paper is to discuss significant aspects related to the implementation and operation of HI in a moderate, transitory climate. The research was carried out from 2011 to 2017. The share of solar collectors in annual heat generation ranged between 7.4% and 12.5%, with an average annual efficiency to 38%. The annual performance of a ground-source heat pump in the heating mode ranged from 3.5 to 3.8, and in the passive cooling mode, it reached up to 11.87. The annual efficiency of a gas condensing boiler was from 77.5% to 82.2%. Annually, the largest amounts of heat were supplied by a biomass boiler i.e. from 30% to as much as 50%. The paper disclosed clearly that it is possible to reach in HI high level of RES share in heat generation. A key issue requiring further research is the development of appropriate algorithms in the control systems of HI.

Switchable thermal insulation, in the form of an opaque panel that alternates between thermally conductive and insulated states, can be an effective means of regulating the thermal environment by selectively transferring heat between the indoor and outdoor environments. Pioneering work has been undertaken by researchers to develop switchable insulation technologies intended for applications in the built environment, automotive, and aerospace, where conventional space heating and cooling technologies are either too bulky or too energy consuming to meet design requirements. Switchable insulation technologies are in their infancy and the emerging research on this topic is unstructured and fragmented across disparate application sectors and very few of the adaptive insulation concepts and technologies are actively being pursued by the buildings research community. The aim of this paper is therefore to advance the understanding of switchable insulation for possible applications in the building envelope, by reviewing and classifying the existing technologies systematically, with a particular focus on their working principles, theoretical performance and improvement opportunities. The paper provides a qualitative and quantitative assessment of the most promising switchable insulation technologies for building envelopes and identifies the opportunities for further research in each of the technologies.

Occupant behaviors are one of the dominant factors that influence building energy use. Traditional building energy modeling programs use typical occupant schedules that often do not reflect actual situations. Robust occupant behavior modeling that seamlessly integrates with building energy models will not only improve simulation performance, but also provide a deeper understanding of occupant behaviors in buildings. This paper presents a development and validation approach to a novel occupant behavior model in commercial buildings. A robust agent-based modeling (ABM) tool, namely Performance Moderator Functions server (PMFserv), is used as the basis of the occupant behavior model. The ABM considers various occupant perceptions and interactions with window, door, and window-blinds based on the environmental conditions. An elaborate agent-based model that represents an office space in an existing building is developed. This is followed by a validation study of the ABM through the use of embedded sensors that capture the indoor ambient conditions and a survey to record actual occupant behaviors. By comparing the recorded behavior data with ABM output, this paper discusses the proposed ABM's prediction ability, limitations, and extensibility. Finally, the paper concludes with the potential of integrating the occupant behavior model with building energy simulation programs.

This paper focuses on the water-energy nexus in low income households. Water, electricity and gas constitute fundamental resources for households that interplay throughout many daily activities. However, in studies on household poverty, there is a tendency to treat water and energy separately. In this contribution, we argue for the joint consideration of both forms of deprivation and present empirical evidence for the Metropolitan Area of Barcelona (AMB). In Barcelona, the dynamics between water and energy poverty in households widened the scope of institutional measures on energy poverty by incorporating water poverty as part of guaranteeing the ‘right to basic utilities’. We document the interactions between the two resources through the water-energy nexus approach by combining quantitative and qualitative methodologies. Apart from presenting the expenditure-based analysis of the Spanish Survey of Income and Living Conditions, which reveals that a significant part of the population is both water and energy poor, with the results from our semi-structured interviews, we are able to demonstrate how much importance and value the affected households give to their thermal and hydric (dis)comfort, which in turn, exerts a direct impact on their daily hygiene and health. The paper also highlights institutional and socio-technical perspective as the differences in ownership and regulatory status of both resources cause discordances in public efforts to alleviate the status of the water and energy poor.

Urban building energy model (UBEM) is an important tool in coping with energy issues of building sector. This paper focuses on an issue that the stock of heating, ventilation, and air-conditioning (HVAC) systems has been oversimplified in UBEM without considering its heterogeneity. It has been observed that this oversimplification may incur a significant error in the result. To address this issue, this paper proposes a framework that integrates a logistic regression based HVAC system stock modeling method and the bottom-up type engineering modeling method using building archetypes considering HVAC system configurations. A case study with Japanese office building stock revealed that (1) the disregard of the heterogeneity resulted in an error of 15% in the annual primary energy consumption, (2) the historical change in the HVAC system stock could decrease the consumption up to 5%, and (3) its composition has a significant influence on the energy saving due to energy efficiency increase in heat source machines used in HVAC systems. The presented method would contribute not only to improving the reliability of UBEM but also to providing an analytical capability of considering energy efficiency technologies related to HVAC systems along with the alternation of technology selection in the building stock.

Academic interests into energy poverty have been growing since the 1990s. These have ranged from quantitative measures and qualitative reflections, as well as ones that aimed to provide more nuanced definitions. These studies have, however, typically focused on single jurisdictions or across national borders, with very few examining the issue across different climatic and policy contexts within the same nation. This paper aims to address this gap by focussing on differences in climate conditions, local policies and quality of the housing stock across Australia and reflects on how these factors each played a role, to varying degrees, in the prevalence of energy poverty amongst lower-income households across eight metropolitan and regional settings conducted as part of a recent study in Australia. Through a review of focus group, interview and workshop data, it especially highlights the more qualitative impacts of energy poverty, and how each of these factors come to influence the extent to which lower-income households experience energy poverty and the support they were able to access. Additional to the need for more contextualised measures of energy poverty, this paper calls for localised responses to alleviate the negative outcomes reflected by our participants in regard to both energy and housing policies.

Vacuum insulation panels (VIPs) represent a huge opportunity to achieve nearly zero energy buildings, especially in the retrofitting of existing buildings. VIPs can be applied in conjunction with façade cladding elements, considerably reducing the heat losses or gains from the building by means of very slim wall construction systems or retrofit solutions. However, the fact that VIPs cannot be cut on-site, can be easily damaged during their handling, installation and use and have an envelope that can cause thermal bridging in the junction between panels or when combined with other materials, has hindered their penetration in the construction market. This paper presents two innovative façade retrofitting solutions, a rear ventilated façade and a stud mounted internal solution, that have tackled all these issues and provide thermal transmittances of 0.28 and 0.14 W/m2 K in relatively slim insulation systems of 10 cm widths. Solutions have been installed on the entire façade of two existing buildings located in Bilbao (Spain) and Malmö (Sweden) subjected to an integral rehabilitation process, covering 2100 m2. Buildings energy use have been monitored before and after the renovation, showing energy cuts of around 35% from pre-intervention status. This paper presents the lessons learnt during the design and installation process of the vacuum insulation integrating solutions in the façade of two existing buildings and the thermal performance results achieved after their retrofitting. Thanks to A2PBEER project for providing the resources. This project has received funding from the European Union’s Seventh Framework Programme for research, technological development and demonstration under grant agreement no 609060. This paper reflects only the author’s views and the Union is not liable for any use that may be made of the information contained there in.

As hot days are getting hotter and more frequent, urban dwelling is expected to increase cooling energy use in current and future climate. The applicability of dynamic building simulation in estimating cooling loads of a city's housing stock can be limited due to lack of fine-grained on-site current and future weather inputs. For predicative modelling of residential cooling energy demand to aid a city's energy supply planning resilient to excessive heat conditions, it requires cooling energy demand projection based on a relational account of (1) the thermal-environmental interaction between housing stocks and urban microclimate conditions, (2) the city dwellers' cooling energy use behaviour, and (3) the city's climate projections. In this paper, we introduce an ‘archetype-in-neighbourhood’ framework to meet these requirements. Combining empirical urban data modelling and EngeryPlus model calibration, this framework was developed to obtain statistically a maximal cooling energy demand model of a city's housing stock during yearly hottest periods. We applied the framework to multiple datasets selected from Seoul's open urban data sources for the period of 2014–2017 (2014 being the earliest year of data availability, 2017 being the end of the study period), including metered electricity use data of 659 apartment buildings (51,351 households) sampled from 18 city districts. The results show that maximal month cooling energy demand (MMCD, kWh/m2) of Seoul's housing stock can be expressed as a regression function of two determinants: (1) the city's average outdoor temperature during the hottest month period (Tex, °C), and (2) estimated indoor cooling temperature set-point (Tin, °C) of the city’ housing stock during the same period. Through a k-fold (k = 4) validation, the current regression model (2014–17) was evaluated to have an overall coefficient of determination R2=0.969. Assuming no housing stock renovation, we applied the model to generate scenarios of maximal month cooling demand in future years according to some of the highest summer temperatures projected for Seoul (RCP8.5 2045, RCP4.5 2047, MM5 2071–2100). We conclude this paper with a brief discussion of the implication for cooling energy supply planning and further work to extend the applicability of this new framework to housing stock adaptation planning and design.

International audience; The paper has a focus on energy consumption habits, trends and intervention strategies in residential buildings, mainly through the serious game approach with a combination of direct consumer feedback through smart metering. More than 150 homes in France and Spain have been involved in the research experiment and the consumption habits of approximately 50 homes were deeply analyzed. The applied methods, processes, results and findings of the monitoring data analysis are presented in the paper with two aims. First, consumption profiles and trends were determined for apartment homes with regard to heating, domestic hot water and electric consumption. Second, the impact of a serious game experiment was assessed comparing energy consumption, indoor air temperature and users' habits (based on questionnaires) before and after launching the experiment.

Heating electrification and distributed renewable generation in the residential sector are among prominent solutions advocated for energy saving and carbon emission reduction. However, research shows these low-carbon technologies may create issues at the low-voltage (LV) distribution grid. High-level policy assessment currently lacks the support to take into account such local grid restrictions. To achieve this, we propose the use of a probabilistic simulation framework in combination with metamodeling, that allows to assess the potential LV grid impact for a wide range of cases. The probabilistic framework is first presented, which is developed for Belgian residential neighborhoods with air-source heat pumps and rooftop PV, based on previous work. Given the complexity and computational requirements of this approach, the paper furthermore proposes metamodeling as a technique to obtain inexpensive evaluation of low-voltage grid impact indicators, suitable for high-level assessments. Although metamodeling is extensively used in various engineering domains, no application in district-level grid-related indicators is available. Consequently, this paper’s focus lies on discussing the various steps and options of the metamodeling procedure, while emphasizing problem-specific challenges. Lastly, the proposed metamodeling methodology is used for training simple metamodels for voltage indicators in neighborhood-level LV grids. Linear regression performed fairly well in predicting the minimum voltage levels, though less accurately close to the lower voltage limit, while logistic regression effectively detected feeders with violations.

Green buildings and neighborhoods can help mitigate impacts of buildings on the environment, society and economy. Many rating systems or tools have been developed worldwide to assess and certificate green buildings or green neighborhoods. Renewable energy plays an important role in achieving green buildings/neighborhoods or zero energy buildings/neighborhoods by reducing fuel consumption and pollution emissions. However, substantial differences exist in assessing or quantifying the renewable energy in green building/neighborhood rating systems. This paper therefore provides a comprehensive review on renewable energy assessment methods adopted in green building/neighborhood rating systems, which would be very helpful to understand and then improve the rating systems. These methods are analyzed and discussed regarding to the calculation way, involved renewable energy types, building characteristics and energy conversion. Then a case study is conducted to quantitatively illustrate the difference of typical renewable energy assessment. Suggestions are summarized to improve the assessment methods. This paper will help investors, users and policy makers understand the rating systems more thoroughly and promote the development of green buildings and green neighborhoods.

Due to global climate change, carbon reduction has become a critical issue for the construction industry. Low carbon building has been adopted as a strategic objective, and its implementation demonstrates the enormous potential of reducing carbon emissions. Despite much research, some important research areas or gaps have not been identified, while simultaneously, few studies describe the knowledge roadmap for low carbon building research necessary to guide scholars and practitioners. The purpose in this paper is to provide a comprehensive and objective analysis of research areas regarding low carbon building using the scientometrics method. A total of 378 low carbon building-related publications were reviewed. Based on the keyword co-word analysis, document co-citation analysis and clustering analysis, the results show that 100 research keywords, 3 research hotspots and 5 research domains are extremely important for the advancement of low carbon building. Based on the in-depth analysis of the findings, the knowledge structure with different prominences was developed, which grouped LCB research into five themes and various sub-topics. Significantly, this paper provides the knowledge roadmap needed to facilitate further research and applications for both academia and industry stakeholders to improve low carbon building.

© 2019 Elsevier B.V. This paper explores the concept of characterizing the as-built Heat Loss Coefficient (HLC)of buildings based on-board monitoring (OBM), via energy consumption and temperature sensors, and time series analysis. It is examined (1)how the coefficients of different Auto-Regressive with eXogenous inputs (ARX)models can be interpreted and (2)whether these conclusions are sensitive to the building envelope assembly or the applied indoor temperature profile. The paper presents a theoretical case study whereby detailed building energy simulations are used to accurately map the impact of physical phenomena on the characterization process. The simulation models and boundary conditions are composed to focus on the link between the estimated ARX-coefficients and the physical driving forces for transmission heat loss to the ground and the exterior environment. The results show how the various ARX model coefficients are linked to specific components of the HLC (e.g. heat transfer through the walls and roof or through the slab-on-ground floor)and to what extent they are affected by the selection of input variables. By monitoring the ground temperature, the transmission heat losses can rather accurately be assigned to either the slab-on-ground or the walls and roof. Without this measurement data, the uncertainty on the estimates increases (ranges of the 95% confidence interval of up to 35% of the mean estimate). Modeling the ground heat losses by a constant intercept term leads to underestimations of the reference HLC of up to 59%, whereas adding heat flux sensors to monitor the transmission heat losses to the ground to the measurement set-up allows to assess the transmission heat transfer coefficient to the exterior environment HLC e within 2%. ispartof: ENERGY AND BUILDINGS vol:195 pages:180-194 status: published

In order to meet ambitious greenhouse gas reduction targets, the reduction of fuel consumption in the heating sector is necessary. This paper assesses the impact of introducing direct drain water heat recovery systems in commercial kitchens in the UK, based on a commercially available heat exchangers. The recoverable heat from these kitchens was estimated using Monte Carlo simulation, sector consumption data, and data measured in the field. A financial criterion, the Net Present Value calculated over 10 years, was used to estimate feasibility threshold values for the kitchen water consumption, varying with the heating fuel used in each premises. This analysis resulted in a total financially feasible potential for drain water heat recovery in the hospitality and food service sector in the UK of approximately 1.24 TWh/yr, leading to a reduction in GHG emissions of 344 k tons Ce/yr. This could be achieved at a cost of approximately 2.94 p£/kg Cesaved, over a 10-year lifetime, which was several orders of magnitude smaller than traditional renewable heat sources such as heat pumps. Commercially available drain water heat recovery systems could, when installed, exploit around 88% of current potential in drain water heat in commercial kitchens (1.40 TWh/yr) in a manner that is financially profitable. However, this paper assumes the availability of a 2 m vertical drop in the kitchen drain, required to install the heat exchanger, and thus achieve optimal effectiveness. In case this head is not available, the heat recovery potential would be untapped, as in approximately 160 GWh, in kitchens where the hot water consumption is too small for financial profitability. This corresponds to a reduction in GHG emissions of 44 k tons Ce/yr and leaves a gap in the market for inexpensive DWHR devices, which could exploit this potential at lower efficiencies.

The identification of heating load patterns, also known as load profiles, is of vital importance to effective management and operation of district heating system (DHS). Clustering algorithms have been successfully applied in identifying heating load patterns. In this paper, we propose that the heating load patterns should be analyzed more specifically, and Gaussian Mixture Model (GMM) clustering is selected to extract sub-patterns. The novelty of this paper is that a new GMM clustering is applied to identify temperature related sub-pattern and people behavior related sub-pattern, and the clustering result is further utilized to improve the accuracy of prediction models. An energy station in Tianjin is used as case studies and four typical operation patterns are found with their characteristic of occur time and energy signature, which are defined as working pattern, on-duty pattern, daytime–nighttime pattern and nighttime–daytime pattern. The results reveal that this proposed method can make an in-depth identification of heating load patterns and also proves that the prediction accuracies of regression and artificial intelligence model are significantly improved by utilizing the GMM clustering results.

Following the 1960s environmental movement and the energy crisis in the 70s, evidence spurred research on renewable energy and energy efficiency practices. As a result, the green building (GB) movement emerged in the 90s to promote buildings which are designed to reduce the consumption of energy, electricity, water, materials, natural resources as well as improve environmental performance and human health over the whole lifecycle. With a prime goal of improving energy efficiency, GB has gained recognition in national and international energy policies. Following manifold exemplary projects and testified benefits, GBs research has recorded a tremendous increase over the years. Thus, it is essential to monitor the research progress to identify areas that require further research. This paper recruited the bibliometric data of 1147 GBs research articles and conducted a scientometric review. The review showed that GBs research publications increased steadily from 1992 to 2018. This highlights the increasing commitment towards the initiative. The paper found that at least 44% of all countries in the world are involved in GBs research. Ten (10) broad GB research areas in existing studies were identified and discussed and areas for further research were proposed. Thus, the paper offers a useful reference point to early-stage researchers, funding authorities, energy policymakers and industry professionals on the research progress in GBs.

Studies of energy poverty have proliferated around the world. While the existing literature provides significant insights into the drivers and dynamics of energy poverty in some parts of the world, there remains little evidence from Asia – a region that combines rapidly changing developed urban conurbations alongside widespread rural poverty. This paper explores a case study of energy poverty in Hong Kong – a global city with high levels of inequality and housing precarity. To date, there has been no published academic work on this topic in the Hong Kong context, and little work in urban Asia. This paper draws on documentary analyses and interviews to present three narratives around the emergence and manifestation of energy poverty in Hong Kong: (a) energy systems, markets and policy (b) urban poverty and inequality and (c) energy services and cooling. By reading energy poverty ‘through the city’, the paper emphasises the importance of geographically sensitive accounts and proposes an agenda for future research. It thus enables the study of energy poverty to be productively pursued in the context of Hong Kong and urban Asia more broadly.

This paper explores the most influential aspects regarding the environmental and economic performance of zero-energy and zero-emission buildings and proposes a pathway for transition in building solutions. A representative zero-energy office building in Norway is investigated with alternative design solutions to achieve zero-emission status i.e., the extensive use of locally generated energy through photovoltaic (PV) panels and the use of materials with low embodied emissions, such as low-carbon concrete and wood. A life cycle environmental and economic assessment is performed to evaluate specific indicators during the building life cycle: cumulative energy (CED), global warming potential (GWP), and equivalent annual cost (EAC). The extensive use of PV panels was most effective in lowering the operational energy because it reduced the CED by about 30% compared to the building as-built. However, the extensive use of wood in the construction contributed the most to GWP reduction, with around 30% decrease compared to the building as-built. Finally, the differences in EAC were interestingly insignificant among the alternatives, with the investment costs dominating the EAC for all designs examined. The findings of this paper emphasise that a full compensation of the life cycle GHG emissions from materials is difficult to achieve through renewable energy, even with extensive use of PV panels, especially in a low-carbon grid situation as in Norway. A pathway strategy from zero-energy towards zero-emission buildings must therefore strongly focus on the materials’ embodied energy and emissions because low operational energy demand is already a regulatory priority in most countries.

The assessment of building energy performance through dynamic simulations has been increasing significantly in recent years since it represents a key strategy for the correct design of highly efficient buildings. Results of dynamic energy simulations are affected by many uncertainties, and its reliability depends on the accuracy of the input variables. One of the most influential variables is the climate surrounding the building, a reason why the use of accurate weather data files is essential, but experimental datasets are not always available. In this context, this paper analyses numerical weather datasets obtained from different regional climate models by comparing them with real data; in addition, it evaluates their impact on the energy performance of a historical building in Asuncion through dynamic simulations. The database of five different weather data sources is compared with observed meteorological data in order to assess their accuracy through statistical analyses. Moreover, some methodologies to estimate diffused and direct components of the global solar radiation are evaluated, with the objective of solving the problem of missing direct and diffused solar data components from the meteorological codes. Subsequently, weather data files are generated to quantify the influence of measured/simulated meteorological data on the evaluation of building energy performance. The results obtained in this paper show that the simulated meteorological data agree very well with real observations for the year under study. Also, the simulations of the building energy performance delivered similar values to those obtained using the real weather dataset. Therefore, the regional climate models can represent a reliable tool for building energy performance assessment, and mainly for the calibration of building energy models when measured weather data is not available.

With increasing proliferation levels of variable energy sources, flexible energy loads will become increasingly important to help stabilize the energy grid. Increasing electrification of heating systems means that the thermal inertia of buildings and hot water vessels can provide a ubiquitous, low cost alternative to electrical storage for providing this energy flexibility. However, it is unclear how this flexibility fluctuates with various factors such as occupant behaviour and ambient conditions in the real world. This paper quantifies the effect of different influencing factors on the energy flexibility of residential hot water systems using data from a large scale real world pilot. All the houses considered in this analysis feature identical air source heat pump hot water systems, along with 200 l storage vessels. It is shown that ambient conditions, control algorithm and occupant behaviour, all influence the available energy flexibility of the hot water system, albeit in different ways. Available capacity for energy flexibility and the corresponding recovery periods can differ by as much as two to four times for identical storage, meaning that these differences should be taken into account during operational planning with flexible loads. Additionally, it is shown that the implemented control strategy provides a meaningful avenue to alter the available energy flexibility. The paper also highlights key differences in the way these factors influence the overall energy demand when compared to available flexibility.

U.S. commercial buildings consumed around 18% of total primary energy in 2017 and a 2.23 EJ increase is expected by 2050. Energy-related data for commercial buildings can be used for various applications, including benchmarking, building component analysis, market potential analysis, and policy making. Although there are plenty of data sources for energy usage in commercial buildings, they have not been thoroughly reviewed and summarized. As a result, users do not have comprehensive guidelines about selections of right data sources for specific application needs. To fill this gap, this paper conducts a comprehensive review to summarize data sources for energy usage in U.S. commercial buildings and discuss their usages for different applications. First, the paper summarizes the survey and simulation data sources for energy usage. The data sources are compared in terms of their data collection methods, released information, and relevant features. Second, this paper analyzes the applications for different survey and simulation data sources. This review categorizes the applications of data sources into five categories, including energy performance benchmarks, energy use forecasts and predictions, energy use contributions of building components, supports of building energy policies, and urban-scale energy use analysis. Moreover, the paper introduces several cases to demonstrate the usages of these data sources.

To assure high quality thermal storage and high efficiency of its acquisition, thermal stratification is often employed in domestic hot water tanks. The whole motivation of stratification lies in the fact that mixing effect can be minimized during operational cycle of the tank so that high temperature water could be taken at the load end, thus maintaining high thermal efficiency at demand side, while low-temperature water can be drawn at lower bottom, thus maintaining the high efficiency at energy collection side. The study of stratification entails the assessment of a wide variety of concepts to be embodied around the central theme of the tank – its design and modelling. This paper presents a systematic review pertaining to various such concepts. For instance, multi-node and plug-flow approach to model various temperature distribution models are considered. These models are categorized in paper as linear, stepped, continuous-linear and general three-zone temperature distribution models. Subsequently, the dynamics of thermocline decay and influencing parameters both during standby and dynamic mode will be demonstrated. In addition, a survey of state of the art methods and practices to ascertain the performance improvement and its quantification will be illustrated. This includes geometrical parameters – such as, structural design incorporation, essentially – inlet design, tank aspect ratio and wall material specification, and also, operational parameters to curb down the inlet mixing. Practice techniques and methods which are presented here in a novel way, extend towards the ground of practical application and research procedures.

Over the last decade, building engineers have begun implementing sensible-latent de-coupled air-conditioning systems in non-residential buildings in hot-humid climates. Typically, a de-coupled system consists of a dedicated outdoor air sub-system for ventilation and high-temperature radiant cooling sub-system for space cooling. This approach has lowered cooling energy demands and fan energy consumption in buildings. However, the complete energy saving potential of de-coupled systems, specifically high-temperature space cooling sub-systems, can only be realized by using low-lift chillers that supply chilled water which matches the high-temperature radiant cooling application. This paper discusses the results of a retro-installation of a prototype modular low-lift chiller to provide high-temperature chilled water (at 17 °C) to the radiant cooling units. The paper presents temperature and cooling load profiles, control methodology and energy efficiency improvements of the low-lift cooling system. The paper also further discusses the influence of various parameters on the performance of the chiller. Despite having a cooling capacity of only 20 kW, the modular low-lift chiller is consistently able to achieve a Coefficient of Performance (COP) of 8. By operating at a low-lift (20 K) compared to a high-lift (29 K), the sensible cooling electrical consumption (at the chiller) is reduced by 23% despite being compared to a high-lift low-temperature chiller with 100 x higher cooling capacity. When normalized for cooling capacities, this reduction is between 29–30%. The project is the first known installation of low-lift cooling for building comfort control in hot-humid climates, and first reported publication of low-lift cooling in a real-life scenario - i.e., non-laboratory conditions or modelling exercise.

The solar chimney is one concept explored by building engineers and designers for reducing heat gain and inducing natural cooling in both commercial and residential buildings. In this sense, scientists around the world have developed significant research on solar chimneys since the 1990s. This review presents the studies related to the numerical thermal modeling of both, conventional solar chimneys and solar chimneys with phase change materials (PCM). The article focuses on two research areas: Computational Fluid Dynamics (CFD) and Global Energy Balance (GEB). Based on the literature, the CFD approach has become a powerful tool to investigate several aspects concerning the heat transfer mechanisms in a solar chimney. Additionally, the analysis of the literature showed that few calculation tools based on CFD transient state models of solar chimneys are available because the computational time required to solve these models could be excessive and impractical. Therefore, the use of high-performance computing (HPC) will be necessary to continue using CFD. On the contrary, the GEB models predict the transient behavior of these systems in short times, and one can integrate them in Building Energy Simulation programs. However, the literature about the solar chimney modeling using GEB shows that the transient mathematical model with PCM (six research papers) has been less used than the steady-state model. In general, results of a solar chimney using a PCM show that the temperature variation of PCM and air in the chimney were available for the natural ventilation in evening and night periods. Finally, this review paper is a reference for future research into the field of solar chimneys with a PCM and its applications.

Due to their significant internal heat gain resulting from computer server banks, data centres require cooling year-round, creating an opportunity to transport the waste heat to heat-deficient neighbouring buildings. This paper evaluates the quantity of multi-unit residential buildings (MURBs) that should be connected to a given data centre in order to maximize the portion of shared energy which provides the MURBs’ heating energy and the data centre's cooling energy simultaneously. The paper then evaluates the financial viability and greenhouse gas (GHG) emissions of three different methods with which energy can be shared from a data centre to surrounding MURBs in a community energy network (CEN). The first method, called the Energy Sharing System involves using a heat pump to produce heating and cooling at the same time for the MURBs and the data centre. The second, called the One-Borefield System, has the same energy sharing aspect as the first, with additional heating and cooling coming from geo-exchange. The third method, called the Two-Borefield System, is an innovative approach to geo-exchange, which uses two separate borefields to achieve free cooling, while also incorporating the energy sharing base. The investigation finds that the optimal MURB area that should be connected to a 4000 kW cooling load data centre is 110,000 m2 for the Toronto (Canada) climate. The financial analysis shows that the Energy Sharing System was the most profitable, with a 11.9% 30-year unlevered after-tax internal rate of return (IRR).

Groundwater seepage plays a role in the heat transfer between ground heat exchanger (GHE) and the surrounding underground medium, and the heat transfer mode is converted from conduction to combined case containing both conduction and convection, which means groundwater seepage inevitably exerts influence on the underground temperature response caused by GHE. The paper describes the equations of underground temperature response while groundwater flows through GHE by means of three-dimensional velocity, and this is the new knowledge differing from traditional one-dimensional velocity. The dimensionless method is employed to conveniently express the formulas; the temperature fields around GHE are investigated to show the influence of groundwater seepage, and the comparisons between without and with groundwater seepage are made. Afterwards, the underground temperature variations of different conditions are analyzed, some stages including cooling period, heating period and transitional period are adopted to analyze the corresponding temperature variations, and the influencing factors for annual underground temperature variation are discussed. In addition, the angles of seepage direction are illustrated, and the temperature response of one location can be changed with the angles. The researches of the paper are novel for further understanding the groundwater seepage.

This paper tackles the issue of frost formation in air-to-air heat recovery devices dedicated to single room ventilation by means of both numerical simulations and experimental approaches. In such heat exchangers, it is commonly known that the formation of a frost layer on the surface generates an additional thermal resistance and a flow section reduction, which leads to an overall degradation of the overall unit performance. This paper proposes a three-zone model, considering a dry, a wet and a frost zone, by determining the location of moving boundaries. Each zone is handled independently and the relative proportion of each zone is determined by means of the exchanger wall temperature. Besides this frost model, a defrost model is also envisaged. Once validated with experimental data collected on a U-flow-type heat exchanger, the developed model is used to implement different strategies to reduce or prevent frost formation in the exchanger. Based on three different criteria, these strategies are compared with each other to evaluate their benefits and drawbacks. The criteria give information on the energy efficiency of the ventilation, on the air renewal quality and on the pressure balance between the inside and the outside of the building.

Ground-coupled heat pump (GCHP) systems are being increasingly utilized in recent years. There are several important parameters in the design of GCHP systems. As ground thermal conductivity is one of the most crucial parameters, it should be measured by conducting in-situ thermal response tests (TRTs). This paper presents the experimental results and analysis of thermal response tests to estimate the ground thermal conductivity and ground thermal diffusivity for three types of ground heat exchangers (GHEs), including U, 2U, and W-type ground heat exchangers (GHEs). Three different types of GHEs were installed in a dredged soil deposit, and continuous TRTs were conducted for 48 h. This study suggests a method to predict ground thermal diffusivity using the infinite line source model from the TRTs. Furthermore, soil samples were collected from different ground layers, and ground thermal properties were measured using laboratory tests. The equivalent ground thermal conductivity and ground thermal diffusivity measured through laboratory tests were compared with the in-situ TRT results that were newly derived in this paper. In addition, ground thermal diffusivity and ground thermal conductivity values that were obtained through research were used as input parameters in numerical analysis. The in-situ TRT results were numerically modeled using the finite element method.