Energy Performance Of Dwellings Research Articles

Exploring assumptions for air infiltration rate estimates using indoor radon in UK homes

Radon, a known carcinogen, is one of the most commonly monitored indoor contaminants. This paper utilises findings from a previous study on indoor radon measurements in United Kingdom (UK) homes to explore the UK Government’s Standard Assessment Procedure (SAP) assumptions for air infiltration rates. These assumptions are important as they are used to assess the energy performance of dwellings and compliance with building regulations. Indoor radon data is aggregated by 16 combinations of home energy efficiency measures (loft and wall insulation, glazing upgrades and draught proofing) and fitted using a simple analytic radon model. We find indoor radon to be inversely proportional to air change rate and proportional to a fit coefficient, k, of 42.2 ± 3.1 (95% Confidence Interval (CI)). We also show that the assumptions within SAP used to estimate home infiltration rates can be modified to include the impact of home energy efficiency which improves the fit (R 2 from 0.38 to 0.51) to the radon data. This work provides evidence to help improve assumptions regarding the effects of home energy efficiency on infiltration rates.

Modelling energy performance of residential dwellings by using the MARS technique, SVM-based approach, MLP neural network and M5 model tree

Several previous studies indicate that the energy consumption of buildings has increased steadily during the last decades all over the world. Residential dwellings in European countries are lawfully required to meet the suitable minimum needs concerning energy efficiency according to the European Directives. Specifically heating, ventilation and air conditioning (HVAC) devices represent most of the energy use in dwellings as they have a principal purpose in controlling the inner climate. Hence, one manner to relieve the constantly growing request for supplementary energy supply is to carry more efficient dwelling designs from the energy point of view, which is to say, with superior energy conservation properties. In this sense, an accurate estimation of the heating load (HL) and cooling load (CL) is needed to calculate the detailed descriptions of the heating and cooling device needed to support comfortable indoor air conditions. The goal of this investigation was to acquire some foretold models to achieve a tangible calculation of the HL and CL (output variables) as a function of 8 specific input variables (concretely, relative compactness, surface area, wall area, roof area, overall height, orientation, glazing area and glazing area distribution) at residential dwellings. These eight input factors have been often employed in the literature about the energy performance of dwellings (EPB) to analyse energy-related themes in dwellings. Moreover, a support vector machines (SVM) approach with distinct kernels, an artificial neural network (ANN) of multilayer perceptron network (MLP) kind and M5 model tree were adjusted to the observed data for evaluation of differences. The outcomes of the current investigation are two-fold. First, the importance (or strength) of each input variable on the HL and CL (output variables) is presented through the MARS model. Secondly, the MARS-relied approximation was the most excellent predictor of the EPB. Indeed, a MARS regression was conducted and coefficients of determination equal to 0.9961 for the HL estimation and 0.9651 for the CL estimation were gotten when this approach was employed to 768 diverse residential buildings, respectively. The concordance between the observed data and those predicted with the MARS approximation verified the satisfactory performance of the latter. Finally, the conclusions of this original investigation are summarised.

The energy performance of dwellings with heat pumps of Dutch non-profit housing associations

ABSTRACT Achieving energy efficiency in the built environment requires extensive efforts in the renovation and adaptation of housing stock. A promising design solution is the heat pump. While gas boiler systems are commonly used in Dutch non-profit housing stock, the share of dwellings with a heat pump grew from 1.6% in 2017 to 3.2% in 2021. However, building characteristics and the energy consumption of dwellings with a heat pump are unclear. Therefore, a dataset of 69,422 dwellings with different types of heat pumps has been examined and compared to dwellings with a traditional HR107 condensing gas boiler. This research reports average characteristics and the average actual energy consumption of dwellings with all-electric, hybrid and gas absorption heat pump systems. Dwellings with a heat pump system are on average of higher building quality, their gas consumption is lower and their electricity consumption is higher than dwellings with an HR107 condensing gas boiler. Detailed insight is provided for dwellings with different heat pump systems and for dwellings with different building characteristics. Further research to determine the energy performance of dwellings with specific heat pump configurations is recommended in light of the energy transition in the built environment.

Benchmarking energy performance: indicators and models for Dutch housing associations

Benchmarking is a method that can be used to measure progress and create awareness about the performance of organisations. Benchmarking the housing stock energy performance of Dutch housing associations can be used to measure and assess progress towards the decarbonisation of the housing stock. A new national climate agreement was signed in 2019, and in 2021 a new method to determine the theoretical energy performance of dwellings came into force in the Netherlands. To benchmark energy performance, a set of indicators is created that adequately represents the performance of Dutch housing associations according to the changed policies. A process involving key stakeholders is presented here to identify, assess and combine possible indicators. These were then integrated into four integrated models, which led to a final benchmark model. A model was chosen that consists of three indicators covering the energy performance of Dutch housing associations. The process and arguments that led to this final model are presented. While applicable within the Dutch context, the method and research results provide generalisable insights for the creation of energy performance benchmarks for building stocks. <em><strong>Practice relevance</strong></em> This paper provides both researchers and policymakers with a practical approach to monitor and benchmark the energy performance of dwellings owned by organisations. An analysis of the Dutch policy context is presented. Examples of possible benchmark indicators are described and evaluated. A method is created to assess indicators and it is shown how to integrate indicators in different benchmark models. The final model consists of three indicators: (1) the average theoretical primary fossil energy consumption (energy label value); (2) the difference between the theoretical heating demand (quality building envelope) and the theoretical maximum heating demand of dwellings; and (3) the average actual CO₂ emissions from gas consumption. Researchers and policymakers from other countries can adapt both the process and the final benchmark model to create similar benchmark models across housing stocks.

Towards a future sustainable housing stock

This thesis examines the energy performance of dwellings of Dutch non-profit housing associations towards a future sustainable housing stock. Improving the energy performance of dwellings aims to improve the quality of dwellings and therewith to lower the actual energy consumption. Lowering the actual energy consumption of dwellings contributes to the battle against climate change. This thesis addresses four studies. Study 1 assesses the energy performance progress of over two million dwellings of Dutch non-profit housing associations between 2017 and 2020. It gives insights into the development of the housing stock, the effect of changes of and within the stock, the effect of characteristics of housing associations and it relates the improvement of the energy performance to the sectoral goal. Study 2 assesses advanced models to improve estimations of actual energy consumption of dwellings and therewith to better estimate the effect of renovation measures on actual energy savings. Study 3 assesses the energy performance of dwellings with heat pumps. It gives insights into the energy performance of dwellings with heat pumps as a promising renovation measure towards a future sustainable housing stock. Study 4 assesses the process to create a model to benchmark the energy performance in a changing policy context. The four studies contribute to the understanding of the improvement of the energy performance of dwellings of non-profit housing associations towards a future sustainable housing stock.

The energy performance of dwellings of Dutch non-profit housing associations: Modelling actual energy consumption

In Europe, the energy performance of dwellings is measured using theoretical building energy models based on the Energy Performance of Buildings Directive (EPBD), which estimates the energy consumption of dwellings. However, literature shows large performance gaps between the theoretically predicted energy consumption and the actual energy consumption of dwellings. The goal of this paper is to investigate the extent to which empirical models provide more accurate estimations of actual energy consumption when compared to a theoretical building energy model, in order to estimate average actual energy savings of renovations. We used the Dutch non-profit housing stock to demonstrate the results. We examined three empirical models to predict the actual energy consumption of dwellings: a linear regression model, a non-linear regression model, and a machine learning model (GBM). This paper shows that these three models alleviate the performance gap by giving a good prediction of actual energy consumption on sectoral cross-sections. However, these models still have shortcomings when predicting the effects of specific renovation interventions, for example newly introduced heat pumps. The non-linear and machine learning model (GBM) outperform the theoretical model in terms of estimating energy savings through renovation interventions.

Patterns of Dwelling Types, Location, and Spaciousness of Living in Norway. Critical Remarks on the Practice of Measuring Energy Performance per Floor Area Only

For decades, energy efficiency has been a key issue in the Norwegian building sector, and energy standards are strict in order to reduce net delivered energy to buildings. Formally, requirements on energy use of dwellings are set by kWh per m2 heated GIA per year, a unit not accounting for dwelling size or number of persons in the households. This study, examining spaciousness of living in relation to dwelling types on an urban scale, shows that dwelling area per resident differs a lot across location and dwelling types. This implies that buildings formally performing the same in terms of following the legislation equally, in reality, may have a very different energy demand per person. When comparing dwelling types, energy demand per floor area and floor area per person is considerably higher for detached dwellings than for apartments. For both dwelling types, the energy demand of the dwellings in use is higher than what is stated in the requirements, and this difference is highest for detached houses. The current practice of measuring energy demand only per floor area is therefore insufficient. To realistically model energy performance of dwellings, measures accounting for dwelling size and number of residents should be included.

Influence of pavements on the urban heat island phenomenon: A scientific evolution analysis

The growth of the population in cities and the increase in the use of construction materials caused the cities' internal temperature to increase, producing the effect known as urban heat island. For this reason, there is scientific interest in mitigation methods of adaptation to this effect in the construction area. The main objective of this research is to analyse the scientific articles published from 1990 to 2019 that relate to pavements and the urban heat island phenomenon, using the SciMAT tool for bibliometric analysis to evaluate the general evolution of this area of science. The analysis was carried out on 107 articles, and a clear evolution was found in the research methodologies of studies of pavements in urban heat island conditions. Until 2008, 73% used field or controlled field experiments. In 2019, this ratio had decreased to 36%, while investigations with laboratory experiments were the most prevalent, at 37% of all investigations. In recent years, interdisciplinary research has focused on the issues of mitigating the effects of urban heat islands together with improving the energy performance of dwellings.

Energy Performance of Dwellings in a Temperate Climate Area of Argentina. An Architectural Proposal

Aim: The research aimed at carrying out a global comparative synthesis of the results of monitoring thermal energy behavior of single-family dwellings and apartments located in the city of Santa Rosa, La Pampa, Argentina; and describing an architectural proposal that considers use of resources (land, morphology, materials and energy), lifestyle of inhabitants (qualitative variables) and critical analysis of the historical problems of the housing deficit in Argentina. Methods: The work includes a typological analysis of clusters of dimensional, morphological and thermo-physical indicators, energy performance and inhabitant’s behavior. Regarding energy heating consumption, multifamily buildings consume 52% less energy than the average single-family dwellings. Results: An architectural proposal taken into account the use of resources and energy efficiency strategies to give an answer to the housing deficit of the area under study showed that the densification of housing provides significant energy and economic benefits, especially if one incorporates passive solar design principles. Apartment blocks (B) and single-family dwellings (H) show 114.3 and 47.6 dwelling/hectare, and as a result, 39.4 and 16.4 inhabitant/hectare. Conclusion: Heating energy saving of B in relation to H is around 32% and the envelope’s cost is reduced to 47%. Argentina’s energy scenario, the possibility of reviewing regulations and building codes, the region’s growth trend in housing construction, the process of building labelling, among others, require a thorough analysis of the information on characteristics of building stock and its energy performance.

Energy Performance Certificates—The Role of the Energy Price

Energy performance certificates (EPCs) were introduced to give property buyers better information about the energy efficiency of dwellings and provide incentives to make energy-efficient investments. Previous studies on the effect of EPCs on property value have yielded divergent results, with some studies finding that energy labels affect property values, but others finding that energy labels have little or no effect. The present paper takes the analysis one step further. Using data on energy prices in combination with transaction data from Oslo, we conclude that not only the energy label, but also the energy performance of dwellings in general, has little to no effect on transaction prices. This result is in line with the inferences of several survey studies, which indicate that when people buy a dwelling, they pay considerably less attention to its energy performance compared with other factors, such as the location, neighborhood, size, garden, and the number of bedrooms.

The energy performance of dwellings of non-profit housing associations in the Netherlands 2017 - 2018

Following regulation of the European Union, objectives were formulated to reduce energy consumption of the built environment in the Netherlands. For the stock of Dutch non-profit housing associations it was agreed to improve the average energy performance to an average energy index of 1.40 in 2020. This research assesses and gives insights in the progress to this objective for over 2.0 million dwellings of over 250 Dutch non-profit housing associations in 2017 and 2018. The assessment consists of an analysis of applied renovation measures, changes of the stock like new construction and demolishing, and clarifying characteristics of housing associations. It is concluded that large urban housing associations with adequate financial positions drive the improvement of the average sectoral energy performance. The improvement happens for a large part within the existing stock, mostly with traditional improvements like improved heating installations and improved insulation. Innovative solutions like: photovoltaic solar systems, combined heat and power systems, biomass systems, heat pumps and external heating, are responsible for a relative small part of the improvement within renovations. New construction and demolishing are also responsible for a relative small part of the annual improvement, but there is potential to improve this.

Evaluation of indoor environment and energy performance of dwellings in heritage buildings. The case of hot summers in historic cities in Mediterranean Europe

The potential benefits for making the historic buildings of heritage cities non-polluting and energy efficient have only recently stirred the interest of researchers and policy makers in facing the necessary challenges. In southern Europe, most of these buildings are residential and are mainly listed at low grades of protection, allowing for significant transformation.This article quantitatively evaluates the indoor environment and energy performance of the residential heritage building stock under the severe summer conditions characteristic of the Mediterranean climate zone. The historic centre of Seville (Andalusia, Spain) is used as a case study. Three dwellings located in representative listed buildings within its conservation area were monitored and analysed taking occupant behaviour into account. The findings show that many dwellings may lack thermal comfort conditions, which cannot always be guaranteed by passive strategies alone. In addition, these buildings are more polluting than recently constructed ones because they depend entirely for their energy supply on the public electricity grid. Interestingly, in most cases reducing the mechanical cooling demand would not require intrusive physical interventions, but would largely rely on suitable window shading and nightly natural ventilation when outdoor conditions allow.

Seasonal Thermal Sensation Vote – An indicator for long-term energy performance of dwellings with no HVAC systems

Dwellings with no heating, ventilation and air conditioning (HVAC) systems are commonly found in many countries. The long-term thermal performance of these buildings can be assessed based on hourly data of occupant thermal discomfort integrated over the required timespan (e.g. total degree hours of discomfort per year). This approach can be easily applied when simulation is adopted in the assessment, but field studies using this approach are rare as they would require complex, costly and long measurement/survey campaigns. This paper addresses the challenges on conducting field studies on long-term thermal performance of dwellings with no HVAC system by introducing a novel performance indicator: the Seasonal Thermal Sensation Vote (S-TSV). S-TSV adopts the standard 7-point thermal sensation scale and is based on the perceived overall thermal sensation recalled by the user of the building for specific seasons and times of day. The new performance indicator is not intended to replace existing ones, but to complement them in the understanding of the complex thermal performance processes taking place in buildings with no HVAC. S-TSV was applied in a field study targeting a small sample of dwellings in Brazil. Results demonstrate the capabilities of S-TSV to describe trends in buildings performance in this sample. S-TSV also assisted on the identification of relationships between such performance and some independent variables addressed in this field study (e.g. windows operation, footwear and income), considering a threshold of p-values <0.05 on the chi-square statistic test.

Methodology for the Study of the Envelope Airtightness of Residential Buildings in Spain: A Case Study

Air leakage and its impact on the energy performance of dwellings has been broadly studied in countries with cold climates in Europe, US, and Canada. However, there is a lack of knowledge in this field in Mediterranean countries. Current Spanish building regulations establish ventilation rates based on ideal airtight envelopes, causing problems of over-ventilation and substantial energy losses. The aim of this paper is to develop a methodology that allows the characterization of the envelope of the housing stock in Spain in order to adjust ventilation rates taking into consideration air leakage. A methodology that is easily applicable to other countries that consider studying the airtightness of the envelope and its energetic behaviour improvement is proposed. A statistical sampling method has been established to determine the dwellings to be tested, considering relevant variables concerning airtightness: climate zone, year of construction, and typology. The air leakage rate is determined using a standardized building pressurization technique according to European Standard EN 13829. A representative case study has been presented as an example of the implementation of the designed methodology and results are compared to preliminary values obtained from the database.

Effects of occupant behavior on the energy performance of dwellings

Chapter 3 is a sensitivity analysis conducted using the actual heating behavior data of occupants in the OTB sample. The aim was to model heating behavior and heating energy consumption using Markov chains and Monte Carlo methods. Secondly we wanted to evaluate the robustness of energy consumption of a dwelling to heating behaviors such as thermostat, radiator and ventilation control, as well as presence. The results of this Chapter were compared to Guerra Santin’s work (2010), which analyzes the same data using correlation and regression analyses. This Chapter deals with the Research Question I of this thesis: “Q I. What is the sensitivity of a dwelling’s heating energy consumption to occupant behavior?" The sub-questions are: 1. What are the existing models developed for the occupant behavior and energy performance relationship? and how different are the results of these models in terms of calculating the influence of occupant behavior on energy performance? 2. How can behavior be modelled in order to assess the robustness of the energy performance in dwellings to occupant behavior? 3. What is the weight of each behavioral aspect in terms of its influence on energy consumption?” The research reported in this Chapter was a collaborative work between Harputlugil and Bedir. The data was collected by a questionnaire prepared by Guerra Santin and Bedir, using OTB’s means of data collection. Data organization and initial statistical analysis was done by Bedir, simulations were conducted by Harputlugil and Bedir together, and finally the evalutation of outputs were done by the same authors. The co-author (G. Harputlugil) has given permission to include this paper in this thesis.

Investigating the consistency and quality of EPC ratings and assessments

Energy Performance Certificates need a degree of consistency if the information provided by these documents are to be used for applications designed to improve the energy efficiency of the building stock of a country. This study demonstrates, through investigations of small samples of dwellings, that the level of quality, and outputs, from a standardised energy assessment can be variable. Multiple assessors evaluating the same property can produce quite markedly different results and, therefore, recommendations for what that household should do to reduce their energy consumption. Using the results of studies conducted by the authors and from elsewhere, qualified commentary is provided relating to what this form of energy assessment should be used for, and whether improvements can be made in the future as areas of policy look to reflect the recorded energy performance of dwellings through a range of policy vehicles.

Assessing the Implementation Potential of PCMs: The Situation for Residential Buildings in the Netherlands

To be able to come to zero-energy buildings we need to apply multiple Energy Techniques and Measures (ETMs). Phase Change Materials (PCMs) can be considered as one of these ETMs and they seem to have a lot of potential. Due to their latent heat capacity, PCMs can help to store energy of our main renewable source, the sun, and to shave energy peaks. However, little is known about what barriers exactly exist in implementing ETMs —and PCMs in particular— in residential buildings. By assessing 1) the effects of PCMs on the energy performance of dwellings, 2) their financial effects and 3) the effects of implementing PCMs for stakeholders, the implementation potential of micro-encapsulated paraffin-based PCMs in Dutch residential buildings is determined and barriers are identified. The observation was made that the effects on the actual energy use cannot be easily estimated and that their impact on compelled EPIs is little. It was also observed that only the investment costs of the PCMs can be assessed and that uncertainty exists about how PCMs perform, when actually implemented in a dwelling and used by residents for several years. Although our experiments on PCMs integrated in concrete floors showed positive results, the implementation potential of micro-encapsulated paraffin based PCMs to support or replace heating systems in residential real estate is relatively low. The results could help developers of new ETMs to become aware of what advantages their innovation can offer and what shortcomings still need to be overcome.

Effects of Occupant Behavior on the Energy Performance of Dwellings: A Sensitivity Analysis

Chapter 3 is a sensitivity analysis conducted using the actual heating behavior data of occupants in the OTB sample. The aim was to model heating behavior and heating energy consumption using Markov chains and Monte Carlo methods. Secondly we wanted to evaluate the robustness of energy consumption of a dwelling to heating behaviors such as thermostat, radiator and ventilation control, as well as presence. The results of this Chapter were compared to Guerra Santin’s work (2010), which analyzes the same data using correlation and regression analyses. This Chapter deals with the Research Question I of this thesis: “Q I. What is the sensitivity of a dwelling’s heating energy consumption to occupant The sub-questions are: 1. What are the existing models developed for the occupant behavior and energy performance relationship? and how different are the results of these models in terms of calculating the influence of occupant behavior on energy performance? 2. How can behavior be modelled in order to assess the robustness of the energy performance in dwellings to occupant behavior? 3. What is the weight of each behavioral aspect in terms of its influence on energy consumption?” The research reported in this Chapter was a collaborative work between Harputlugil and Bedir. The data was collected by a questionnaire prepared by Guerra Santin and Bedir, using OTB’s means of data collection. Data organization and initial statistical analysis was done by Bedir, simulations were conducted by Harputlugil and Bedir together, and finally the evalutation of outputs were done by the same authors. The co-author (G. Harputlugil) has given permission to include this paper in this thesis.

Solid-wall U-values: heat flux measurements compared with standard assumptions

The assumed U-values of solid walls represent a significant source of uncertainty when estimating the energy performance of dwellings. The typical U-value for UK solid walls used for stock-level energy demand estimates and energy certification is 2.1 Wm−2 K−1. A re-analysis (based on 40 brick solid walls and 18 stone walls) using a lumped thermal mass and inverse parameter estimation technique gives a mean value of 1.3 ± 0.4 Wm−2 K−1 for both solid wall types. Among the many implications for policy, this suggests that standard UK solid-wall U-values may be inappropriate for energy certification or for evaluating the investment economics of solid-wall insulation. For stock-level energy modelling, changing the assumed U-value for solid walls reduces the estimated mean annual space heating demand by 16%, and causes a proportion of the stock to change Energy Performance Certification (EPC) band. The analysis shows that the diversity of energy use in domestic buildings may be as much influenced by heterogeneity in the physical characteristics of individual building components as it is by variation in occupant behaviour. Policy assessment and guidance material needs to acknowledge and account for this variation in physical building characteristics through regular grounding in empirical field data.

Comparison and discussion of heating systems for single-family homes in the framework of a renovation

In a global climate of environmental awareness, the expectations regarding energy performance of dwellings are increasingly high. Finding the appropriate heating system in such houses is sensitive. Such a system must meet reduced heating needs while not generating excessive emissions. Emissions would wreck the efforts to reduce the heating needs of these new or renovated homes. Moreover, in a context of economic crisis, the budget allocated to housing is limited. That is why the aim of this study is to evaluate and compare different systems in the framework of energy efficient renovation (i.e., nearly zero energy buildings) to identify which one best meets the current economic and environmental objectives.Different systems are modelled and simulated using TRNSYS in an attached dwelling. They are then evaluated and compared on the basis of their investment, operating, and long-term costs as well as the emissions and primary energy consumption they generate.The main conclusion is that the performance of the heating installation is not the most important factor when choosing a heating system for highly insulated houses. The optimum system identified from an environmental and economic point of view is the recovery of the existing heating installation, followed by installation of a gas-condensing boiler.