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AbstractAn analysis of thermal balance and daylight level in building residential zones is presented in the article. The evaluation is focused on influence of façade thermal insulation layers and multi glass pane windows on reduction of solar gains and daylight level in internal spaces. The evaluation was carried out as a computer simulation study run in software DesignBuilder. The simulation outputs provided information about optimal façade design for energy efficiency and convenient daylighting in buildings under temperate climatic conditions.

A large amount of energy is consumed by heating and cooling systems to provide comfort conditions for commercial building occupants, which generally contribute to peak electricity demands. Thermal storage tanks in HVAC systems, which store heating/cooling energy in the off-peak period for use in the peak period, can be used to offset peak time energy demand. In this study, a theoretical investigation on stratified thermal storage systems is performed to determine the factors that significantly influence the thermal performance of these systems for both heating and cooling applications. Five fully-insulated storage tank geometries, using water as the storage medium, were simulated to determine the effects of water inlet velocity, tank aspect ratio and temperature difference between charging (inlet) and the tank water on mixing and thermocline formation. Results indicate that thermal stratification enhances with increased temperature difference, lower inlet velocities and higher aspect ratios. It was also found that mixing increased by 303% when the temperature difference between the tank and inlet water was reduced from 80 °C to 10 °C, while decreasing the aspect ratio from 3.8 to 1.0 increased mixing by 143%. On the other hand, increasing the inlet water velocity significantly increased the storage mixing. A new theoretical relationship between the inlet water velocity and thermocline formation has been developed. It was also found that inlet flow rates can be increased, without increasing the mixing, after the formation of the thermocline.

Managing thermal comfort, in both hot and cold climates, critically influences energy use in homes [1-4]. For low income households, who commonly live in thermally poor housing stock, maintaining thermal comfort can be costly relative to household income, leading to trade-offs between comfort, energy use and affordability. Comfort as a concept has been explored from many vantages, including as a physiological need [5,6]; a parameter for healthy housing [7]; as an energy efficiency building standard [4,8] and a cultural construct [9,10]. Yet, there is little research available that provides detailed insight into the relationship between thermal comfort and energy efficiency in existing housing stock or about the impact of support programs on these key indicators. This paper reviews measures of household thermal comfort as they relate to energy efficiency assessments in a project, Get Bill Smart (GBS), that worked with low income households in Tasmania, Australia. Thermal comfort and energy use data was collected over 15 months from 51 households, a sub-set of the 510 households participating overall. Longitudinal interviews and housing observations were also conducted. New thermal comfort and energy efficiency indicators were developed from this data. This paper demonstrates the application of these indicators by providing examples of findings in GBS. Suggestions are made for the refinement of measures discussed for use in future applications.

Many efforts are being made to mitigate the main disadvantage of most phase change materials - their low thermal conductivities - in order to deliver latent heat energy storage systems (LHESS) with adequate performance. However, the effect of applied methods is difficult to compare as they are mostly tested for different storage types and sizes and/or different boundary and initial conditions, which hinders rapid progress in the optimization of these approaches. In this work, a previously developed method for comparing the performance of LHESS is applied to experimental results of different storage systems under different conditions and subsequently analyzed and further refined. The main idea of the method is to normalize the power with the volume and a reference temperature difference and compare its mean value plotted over the normalized mean capacity flow of the heat transfer fluid (HTF). This enables the presentation of the results in a compact and easily comparative way. Attention has to be paid when it comes to the choice of the reference temperature difference, the reference volume and the method for calculating the mean value. Two variants of calculating the mean value (time-weighted and energy-weighted) and two variants of reference temperatures for determining the temperature difference to the inlet temperature of the HTF (initial temperature and melting temperature) are applied and discussed in detail. While the method significantly increases the comparability of results, none of the options listed above are without drawbacks. Approaches are shown to reduce or eliminate these drawbacks in the future. The recommendation for comparing different LHESS under different conditions is to use the method described here and clearly state the chosen reference temperature, reference volume and method for calculating the mean value.

This paper presents the performance evaluation of an integrated photovoltaic thermal (PVT) collector-phased change material (PCM) thermal energy storage (TES) system. The PVT collectors can generate both electricity and low-grade thermal energy during the daytime, and the thermal energy generated can be temporarily stored in the PCM TES unit and used for space heating during the night-time. Taguchi method and analysis of variance are used for the simulation design and data analysis, respectively. The thermal performance of the proposed system was evaluated in terms of the useful energy stored in the TES system. The results showed that the outlet air temperature of the TES unit remained at least 2°C higher than the inlet air temperature during the discharging process in the selected test day. The PCM type and the PCM charging air flow rate were the most important factors influencing the useful energy stored in the TES system.

Building regulations in Australia and elsewhere are increasingly directed at reducing greenhouse gas emissions and achieving an efficient use of energy and water. These regulations significantly impact on aspirations with regard to the building design. Five case study houses recognized in awards from the Australian Institute of Architects are investigated for whether they met the aim and criteria of the relevant regulations for energy efficiency and greenhouse gas reductions. Qualitative and quantitative issues surrounding their environmental performance are examined, including occupants' comfort and energy consumption. The findings suggest that the assessment processes underpinning the regulations do not correlate well with measured environmental performance, the perceptions of occupiers, and how these houses are actually designed and operated. The regulatory concept of ‘meeting generic needs’ fails to account for the diversity of socio-cultural understandings, the inhabitants' expectations and their beh...

This paper presents the performance analysis and retrofit assessment of a domestic high temperature air source heat pump coupled with thermal energy storage in terms of different system configurations. TRNSYS simulations were used to model the dynamic system, which has been validated against field trial results. The validated models were then simulated with different system configurations under the same boundary conditions to assess its performances. Simulated results showed that continuous coupling between the heat pump and storage to heat the house had the worst performance, while the operation of only the heat pump heating the house obtained the highest efficiency. Although the heat pump cannot compete with the gas boilers in terms of running costs, between 6.6% and 33% of carbon cut can be achieved if the heat pump was retrofitted.

AbstractThere is growing concern in Western Europe that higher insulation and air tightness of residential buildings leads to increased overheating risk. This paper discusses temperature monitoring from identical houses in the Southwest of the UK that were built to low energy standards (Code for Sustainable Homes Level 5). The temperature data were analysed using both established static overheating criteria (CIBSE Guide A) and an adaptive thermal comfort standard (BSEN15251). The houses can be considered uncomfortably warm during summer and are at risk of overheating. The study suggests that occupant behaviour plays an important role in reducing or increasing internal temperatures.