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The purpose of this paper is to present a methodology for estimating scheduled and manual override heating events and heating settings from indoor air temperature and gas use measurements in UK homes.

Living room air temperature and gas use data were measured in ten UK homes built to low energy standards. The temperature measurements are used to establish whether the central heating system is turned on or off and to estimate the heating setpoint used. The estimated heating periods are verified using the homes' average daily gas consumption profiles.

Using this method, the average number of heating periods per day was 2.2 (SD = 0.8) on weekdays and 2.7 (SD = 0.5) on weekends. The weekday mean heating duration was 8.8 h and for weekends, it was 9.8 h. Manual overrides of the settings occurred in all the dwellings and added an average of 2.4 h and 1.5 h to the heating duration on weekdays and weekends respectively. The mean estimated setpoint temperatures were 21.2 and 21.4°C on weekdays and weekends respectively.

Manual overrides of heating behaviours have only previously been assessed by questionnaire survey. This paper demonstrates an alternative method to identifying these manual override events and responds to a key gap in the current body of research that little is currently reported on the frequency and duration of manual heating overrides in UK homes.

The results could be used to better inform the assumptions of space heating behaviour used in energy models in order to more accurately predict the space heating energy demands of dwellings.

Manual overrides of heating behaviours have only previously been assessed by questionnaire survey. This paper demonstrates an alternative method to identifying these manual override events and responds to a key gap in the current body of research that little is currently reported on the frequency and duration of manual heating overrides in UK homes.

Climate change means that buildings must greatly reduce their energy consumption. It is however paradoxical that climate mitigation in Denmark has created negative energy and indoor climate problems in housing that may be made worse by climate change. A literature review has been carried out of housing schemes where climate mitigation was sought through reduced space heating demand, and it is shown that extensive problems with overheating exist. A theoretical study of regulative and design strategies for climate mitigation in new build housing has therefore been carried out, and it is shown that reducing space heating with high levels of thermal insulation and passive solar energy results in overheating and a growing demand for cooling.

Climate change is expected to reduce space heating and increase cooling demand in housing. An analysis of new build housing using passive solar energy as a climate mitigation strategy has therefore been carried out in relation to future climate change scenarios. It is shown that severe indoor comfort problems can occur, questioning the relevance of passive solar energy as a climate mitigation strategy. In conclusion, a theoretical study of the interplay between climate adaptation and mitigation strategies is carried out, with a cross-disciplinary focus on users, passive design and active technologies. It is shown that the cumulative use of these strategies can create an adaptation buffer, thus eliminating problems with overheating and reducing energy consumption. New build housing should therefore be designed in relation to both current and future climate scenarios to show that the climate mitigation strategies ensure climate adaptation.

The paper aims to clarify the relationship between energy flexibility and building components and technologies. It determines the energy flexibility potential of buildings in relation to their physical characteristics and heat supply systems with respect to external boundary conditions.

The emphasis of the evaluation is based on the timing and the amount of shiftable and storable thermal loads in buildings under defined indoor thermal comfort conditions. Dynamic building simulation is used to evaluate the potential of selected building characteristics to shift heating loads away from peak demand periods. Insights on the energy flexibility potential of individual technologies are gained by examining the thermal behaviour of single-zone simulation models as different input parameters are varied. For this purpose, parameters such as envelope qualities, construction materials, control systems for heating are modified.

The paper provides a comprehensive understanding of the influence of the different building parameters and their variations on their energy shifting potential under “laboratory conditions” with steady boundaries. It suggests that the investigated boundary conditions such as outside temperature, infiltration, envelope quality and user behaviour, which influence the heating load of a building, also influence the resulting potential for energy flexibility. The findings show that the combination of a slowly reacting heat transfer system, such as concrete core activation and a readily available storage mass in the room, and a high insulation standard proved to have a high potential to shift heating loads.

In this paper, energy-flexible components were evaluated in a steady-state simulation approach. Outside temperature, solar irradiation and internal loads over the simulation duration were set constant over time to provide laboratory conditions for the potential analysis. On the basis of both duration and performance of the load shifting or storage event, the components were then quantified in a parametric simulation. The determined energy flexibility is directly related to the power of the heating, cooling, hot water and ventilation system, which can be switched on or off. In general, it can be seen that high power (high loads) demand usually can be switched on and off for a short duration, and low power demand usually for a longer duration. The investigated boundary conditions such as outside temperature, infiltration, envelope quality and user behaviour, which influence the load of a building, also influence the resulting potential for energy flexibility. Higher insulation standards, for example, lead to lower loads that can be switched on or off, but increase the duration of the event (flexibility time). So that, in particular, the shiftable load potential is low but results in a long switch-off duration. Furthermore, passive storage potential in buildings like the storage mass inside the room and the type of heat/cooling transfer system can affect the flexibility potential by more than three times. Especially the combination of a high storage mass and a concrete core heat transfer system can significantly increase the flexibility.

This work is initiated under the premise that reliable evaluation methods are necessary to ensure investments in energy conservation, and the purpose of this paper is to contribute to that literature. It describes some pilot changes and their impact in an actual field study oriented toward upgrading municipal public housing (MPH) units.

The research for this paper was connected to an MPH refurbishment project situated in northern Sweden. The overall energy efficiency goal within the project was a 40-50 percent reduction in the supplied energy for central electricity, domestic hot water and space heating. In order to evaluate if these goals were feasible, a measurement system was installed in a pilot building and in a neighboring building used as a reference. The evaluation was conducted by comparing the post-retrofit performance of the pilot building with the performance of the reference building when it was kept in its initial state (a comparison possible because both buildings had initial similarities).

Impacts could be quantified insofar as a reference (control) building in the same environment was sustained for comparison purposes. A 43 percent improvement was observed in energy utilization in the pilot building compared to its reference companion (99.8 vs 174.5 kWh/m² per year). When the approach described herein was applied to new construction, the present goal of 65 kWh/m² was approached as measured by Swedish standards.

Results should be of interest to academics in the housing field, professionals involved in refurbishment and residents themselves, renting MPH flats.

This study is unique in the following ways: first, it really was a field experiment with a control, thus it did not have any exogenous interference in interpreting results. To the best of our knowledge, this is the first study of its kind. The second interesting characteristic was that results were subsequently used in the refurbishment of other buildings in the complex and in the construction of others. The major value of the paper may be associated with its timing. It comes at a time when the Kyoto agreement has raised concerns about sustainability, but also at a time when many buildings are facing a need for refurbishment.

This paper describes the results of an extensive search into two factors which effect, to a high degree, the efficiency of on‐line information retrieval. These two factors are firstly the manner by which keywords are chosen as a means of retrieval by the reviewers of the reference work and secondly the degree with which papers with comparable contents are accorded similar keywords. The influence of these two factors on the practical results of on‐line retrieval is shown by the example of two extensive searches: these searches were done manually as well as on‐line. From these two methods it is then possible to compare what is retrieved by the computer and what is in reality available.

The aim of the research is to determine the influence of photovoltaic (PV) installation and the share of façade glazing on the energy profile of nursery buildings in the Baltic Sea region, as well as defining the most favorable configuration in terms of energy efficiency.

The article provides comparative calculations of energy performance indicators (Ep, Ed, Eu) and CO₂ emissions (mCO₂) made for the defined model of the nursery. It includes calculations concerning energy performance of the building, depending on its PV power (0–60 kWp), PV efficiency (100 and 85%) and façade glazing ratio (GR = 25%, 50% and 75%).

The results of the research indicate that an increase in the PV power exerts proportional impact on the reduction of the Ep and Ed indicators, as well as on the CO₂ emissions. Only low GR values (25%) reduce the Eu indicator significantly. Decrease in high range of GR values (over 50%) does not provide proportional effects. In the variant: 60 kWp (100% efficiency) with GR = 25%, the biggest share (99.5%) of RES was obtained. This proves that the concept of energy independent nursery buildings is feasible and reasonable in the examined location.

Designing buildings towards environmental neutrality requires laborious pre-design conceptual work before developing the right solutions. The set of results of the relationship between the variables of the building's envelope, energy performance indicators and the required involvement of active RES installations to achieve high energy performance of a building presented in the article is valuable. It allows for a preliminary decision of the direction of the design solutions selection in the design process of public utility buildings, such as nurseries. Thus, it may significantly shorten the pre-design analysis process for the location of the southern part of the Baltic Sea region.

The novelty of the paper relies on examining the dependences between PV power and façade glazing ratio in terms of their influence on energy profile of nursery buildings.

Mechanical ventilation with heat recovery (MVHR) is increasingly being promoted in the UK as a means of reducing the CO₂ emissions from dwellings, and installers report growing activity in the retrofit market. However, the airtightness of a dwelling is a crucially important factor governing the achievement of CO₂ reductions, and the purpose of this paper is to understand the technical implications of airtightness levels in an experimental dwelling, purpose built to typical 1930s standards, at the same time as gaining the users’ perspectives on airtightness and ventilation in their homes.

In‐depth interviews were carried out with 20 households to collect information on their retrofit and improvement strategies, attitudes to energy saving and their living practices as they impinge on ventilation. The experimental house was sealed in a series of interventions, leading to successive reductions in the air permeability as measured by a 50 Pa pressurisation test. The behaviour of a whole‐house MVHR system installed in the experimental house, was simulated using IES Virtual Environment, using a range of air permeability values corresponding to those achieved in the retrofit upgrading process.

In the house considered, air permeability must be reduced below 5 m³/m²h for MVHR to make an overall energy and CO₂ saving. However, to achieve this required a level of disruption that, on the basis of the views expressed, would be unlikely to be tolerated by owners of solid wall dwellings.

The paper is the first to combine results from a user‐centred approach to exploring the existing practices of householders with a simulation of the energy and CO₂ performance at different levels of airtightness of an experimental house in which MVHR has been installed.

This paper aims to investigate the impact of heat recovery ventilators (HRVs) on the energy use and indoor radon in a one family detached house. Heat recovery ventilation systems, because of reducing ventilation loss through recovered exhaust air, can play a good role in the effectiveness of ventilation to reduce energy use. In addition HRVs can maintain pressure balance and outdoor ventilation rate at a required level to mitigate indoor radon level.

In this study, a multizone model of a detached house is developed in IDA Indoor Climate and Energy (IDA ICE 4.0). The model is validated using measurements regarding use of energy for heating, ventilation and whole energy use. The performance of the heat recovery ventilation system is examined with respect to radon mitigation and energy saving by measuring the radon concentration and analyzing the life cycle cost of a heat exchanger unit.

The results of the measurements and dynamic simulation showed that the heat recovery ventilation system could lead to 74 per cent energy savings of the ventilation loss, amounting to about 30 kWh m⁻² per year. Life cycle cost analysis used for assessing total costs and the result showed that using this system is quite cost‐effective and investment would payback during 12 years.

Limitations of this study generally refer to radon measurement and simulation because of radon complex behavior and its high fluctuations even during short periods of time.

Heat recovery ventilation systems with reducing radon concentration improve indoor air quality and decrease environmental problems with energy savings.

Using balanced heat recovery ventilation can have benefits from the viewpoint of environmental impacts and household economy.

Employment of a heat recovery unit to control indoor radon level is a new usage of this technology which along with energy savings can improve sustainable development.

To modify a conventional evacuated tube, an improved asymmetric U-type evacuated tube (AUET) is proposed. This study aims to investigate the thermal and hydrodynamic performances of a modified tube and determine the optimal structural form.

Based on the variation of fluid proprieties with temperature, the formulated numerical model was validated and then deployed to investigate the natural circulation in the evacuated tubes. A dimensionless number was proposed to quantify the stratification effect. The influence of the degree of asymmetry of U-type evacuated tubes on the flow patterns, mass flow rate, temperature distribution, thermal stratification and energy conversion efficiency was studied.

When the degree of asymmetry is large, a higher velocity and better thermal stratification are achieved, thereby avoiding stagnant water at the bottom of the tubes simultaneously. Compared with the conventional evacuated tube, the improved evacuated tube exhibited a higher thermal efficiency.

The originally proposed AUET was proven to have better performance in avoiding stagnant water, reducing fluid mixing and improving the heat transfer efficiency.

The purpose of this paper is threefold: to investigate why and how companies in voluntary networks engage in performance benchmarking; how requirements for a standardised chart of accounts are handled; and what the role of regulatory pressure is.

The paper is based on a longitudinal case study of an established group of six district-heating companies. The data sources are semi-structured interviews, observations and documents.

Both the forthcoming re-regulation of the district-heating sector and aims to improve efficiency were motivating the collaboration among the firms. An interpretation of common accounting rules can be negotiated in a collaborative network. The benchmarking model was embedded in routines internally in firms to facilitate learning and knowledge exchange, but it was also used to legitimise current operations.

As the paper is based on a case study of a specific project, the issues discussed in the paper should be further investigated in similar firms being exposed to regulation.

Harmonisation of accounting data are of immense importance when benchmarking performance, but discretion in interpretations of data and results must be handled. Co-existence with existing rules and procedures should be allowed.

The paper contributes to research understanding the role of collaboration in voluntary networks when benchmarking is implemented.