scholarly journals The Energy Performance Gap in Swiss residential buildings: a roadmap for improvement

2021 ◽  
Vol 2042 (1) ◽  
pp. 012143
Author(s):  
Stefano Cozza ◽  
Jonathan Chambers ◽  
Martin K. Patel
Keyword(s):  
Energy Consumption ◽  
Residential Buildings ◽  
Qualitative Interviews ◽  
Energy Performance ◽  
Extensive Literature ◽  
Existing Buildings ◽  
Accurate Calculation ◽  
Performance Gap ◽  
The Difference ◽  
Theoretical Energy Consumption

Abstract This work deals with the Energy Performance Gap (EPG) in buildings, defined as the difference between actual and theoretical energy consumption. This paper investigates how to close the EPG of existing buildings in Switzerland, by which measures, until when, and at which costs. To address these questions an extensive literature review was conducted combined with qualitative interviews in order to better understand practitioners’ experience and to support the findings from the literature. Several approaches have been found to reduce the EPG. These include both measures to make the building consume as expected and to arrive at a more accurate calculation of the theoretical consumption. We highlight the most relevant solutions for the Swiss context.

scholarly journals Bridging the energy gap of India’s residential buildings by using rooftop solar PV systems for higher energy stars

Clean Energy ◽  
2021 ◽  
Vol 5 (3) ◽  
pp. 423-432
Author(s):  
Rakesh Dalal ◽  
Kamal Bansal ◽  
Sapan Thapar
Keyword(s):  
Energy Consumption ◽  
Economic Analysis ◽  
Residential Buildings ◽  
Electricity Consumption ◽  
Energy Performance ◽  
Solar Pv ◽  
Existing Buildings ◽  
Pv Systems ◽  
Rooftop Solar

Abstract The residential-building sector in India consumes >25% of the total electricity and is the third-largest consumer of electricity; consumption increased by 26% between 2014 and 2017. India has introduced a star-labelling programme for residential buildings that is applicable for all single- and multiple-dwelling units in the country for residential purposes. The Energy Performance Index (EPI) of a building (annual energy consumption in kilowatt-hours per square metre of the building) is taken as an indicator for awarding the star label for residential buildings. For gauging the EPI status of existing buildings, the electricity consumption of residential buildings (in kWh/m2/year) is established through a case study of the residential society. Two years of electricity bills are collected for an Indian residential society located in Palam, Delhi, analysed and benchmarked with the Indian residential star-labelling programme. A wide EPI gap is observed for existing buildings for five-star energy labels. Based on existing electricity tariffs, the energy consumption of residential consumers and the Bureau of Energy Efficiency (BEE)’s proposed building ENERGY STAR labelling, a grid-integrated rooftop solar photovoltaic (PV) system is considered for achieving a higher star label. This research study establishes the potential of grid-connected rooftop solar PV systems for residential buildings in Indian cities through a case study of Delhi. Techno-economic analysis of a grid-integrated 3-kWp rooftop solar PV plant is analysed by using RETScreen software. The study establishes that an additional two stars can be achieved by existing buildings by using a grid-integrated rooftop solar PV plant. Payback for retrofit of a 3-kWp rooftop solar PV plant for Indian cites varies from 3 to 7 years. A case study in Delhi, India establishes the potential of grid-connected rooftop solar PV systems for residential buildings. Techno-economic analysis of grid integrated, 3 kWp rooftop solar systems estimates a payback period from 3 to 7 years.

Development of a numerical approach to assess the effect of coupled heat and moisture transfer on energy consumption of residential buildings in Moroccan context

2021 ◽  
pp. 174425912110560
Author(s):  
Yassine Chbani Idrissi ◽  
Rafik Belarbi ◽  
Mohammed Yacine Ferroukhi ◽  
M’barek Feddaoui ◽  
Driss Agliz
Keyword(s):  
Energy Consumption ◽  
Building Materials ◽  
Moisture Transfer ◽  
Residential Buildings ◽  
Building Design ◽  
Energy Performance ◽  
Climatic Conditions ◽  
Heat And Moisture Transfer ◽  
Coupled Heat And Moisture ◽  
Heat And Moisture

Hygrothermal properties of building materials, climatic conditions and energy performance are interrelated and have to be considered simultaneously as part of an optimised building design. In this paper, a new approach to evaluate the energy consumption of residential buildings in Morocco is presented. This approach is based on the effect of coupled heat and moisture transfer in typical residential buildings and on their responses to the varied climatic conditions encountered in the country. This approach allows us to evaluate with better accuracy the response of building energy performance and the indoor comfort of building occupants. Annual energy consumption, cooling and heating energy requirements were estimated considering the six climatic zones of Morocco. Based on the results, terms related to coupled heat and moisture transfer can effectively correct the existing energy consumption calculations of the six zones of Morocco, which currently do not consider energy consumption due to coupled heat and moisture transfer.

scholarly journals Understanding the Reasons behind the Energy Performance Gap of an Energy-Efficient Building, through a Probabilistic Approach and On-Site Measurements

Energies ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 6178
Author(s):  
Pierryves Padey ◽  
Kyriaki Goulouti ◽  
Guy Wagner ◽  
Blaise Périsset ◽  
Sébastien Lasvaux
Keyword(s):  
Energy Efficient ◽  
Probabilistic Approach ◽  
Energy Performance ◽  
High Energy ◽  
Performance Gap ◽  
Post Evaluation ◽  
Energy Efficient Buildings ◽  
Ex Post ◽  
The Difference ◽  
Energy Efficient Building

The performance gap, defined as the difference between the measured and the calculated performance of energy-efficient buildings, has long been identified as a major issue in the building domain. The present study aims to better understand the performance gap in high-energy performance buildings in Switzerland, in an ex-post evaluation. For an energy-efficient building, the measured heating demand, collected through a four-year measurement campaign was compared to the calculated one and the results showed that the latter underestimates the real heating demand by a factor of two. As a way to reduce the performance gap, a probabilistic framework was proposed so that the different uncertainties of the model could be considered. By comparing the mean of the probabilistic heating demand to the measured one, it was shown that the performance gap was between 20–30% for the examined period. Through a sensitivity analysis, the active air flow and the shading factor were identified as the most influential parameters on the uncertainty of the heating demand, meaning that their wrong adjustment, in reality, or in the simulations, would increase the performance gap.

scholarly journals Development of Energy Benchmarks for Office Buildings Using the National Energy Consumption Database

Energies ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 950 ◽  
Author(s):  
Hye Gi Kim ◽  
Sun Sook Kim
Keyword(s):  
Energy Consumption ◽  
Energy Performance ◽  
Performance Assessments ◽  
Statistical Characteristics ◽  
Limited Information ◽  
Existing Buildings ◽  
Evaluation Systems ◽  
Floor Area ◽  
Consumption Data ◽  
Performance Benchmark

In an effort to improve the energy efficiency of existing buildings, it is necessary to first evaluate the energy performance of those buildings. Since it is difficult to obtain detailed information on existing buildings, the challenge is how to conduct reliable energy performance assessments with this limited information. As a result, many countries have adopted evaluation systems based on measured energy consumption data for existing buildings. This study aims to analyze the building energy consumption and characteristics using Korea’s national building database and provide an energy performance benchmark for continuous management of the energy performance of existing buildings. We analyzed the relationship between the basic statistical characteristics of the information collected from the national integrated energy database and energy consumption. The total floor area was found to be closely related to energy consumption, and various regression analysis methods were applied and compared to develop a benchmark to explain the trends of energy consumption according to the increase in total floor area. Finally, the developed benchmarks were used to evaluate energy consumption and examine the feasibility of the benchmarks.

scholarly journals Application of Rough Set Theory (RST) to Forecast Energy Consumption in Buildings Undergoing Thermal Modernization

Energies ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1309 ◽  
Author(s):  
Tomasz Szul ◽  
Stanisław Kokoszka
Keyword(s):  
Energy Efficiency ◽  
Energy Consumption ◽  
Set Theory ◽  
Rough Set ◽  
Energy Demand ◽  
Rough Set Theory ◽  
Residential Buildings ◽  
Simple Procedure ◽  
Energy Performance ◽  
Improve Energy Efficiency

In many regions, the heat used for space heating is a basic item in the energy balance of a building and significantly affects its operating costs. The accuracy of the assessment of heat consumption in an existing building and the determination of the main components of heat loss depends to a large extent on whether the energy efficiency improvement targets set in the thermal upgrading project are achieved. A frequent problem in the case of energy calculations is the lack of complete architectural and construction documentation of the analyzed objects. Therefore, there is a need to search for methods that will be suitable for a quick technical analysis of measures taken to improve energy efficiency in existing buildings. These methods should have satisfactory results in predicting energy consumption where the input is limited, inaccurate, or uncertain. Therefore, the aim of this work was to test the usefulness of a model based on Rough Set Theory (RST) for estimating the thermal energy consumption of buildings undergoing an energy renovation. The research was carried out on a group of 109 thermally improved residential buildings, for which energy performance was based on actual energy consumption before and after thermal modernization. Specific sets of important variables characterizing the examined buildings were distinguished. The groups of variables were used to estimate energy consumption in such a way as to obtain a compromise between the effort of obtaining them and the quality of the forecast. This has allowed the construction of a prediction model that allows the use of a fast, relatively simple procedure to estimate the final energy demand rate for heating buildings.

scholarly journals Systematic Simplified Simulation Methodology for Deep Energy Retrofitting Towards Nze Targets Using Life Cycle Energy Assessment

Energies ◽  
2019 ◽  
Vol 12 (16) ◽  
pp. 3038 ◽  
Author(s):  
José Sánchez Ramos ◽  
MCarmen Guerrero Delgado ◽  
Servando Álvarez Domínguez ◽  
José Luis Molina Félix ◽  
Francisco José Sánchez de la Flor ◽  
...  
Keyword(s):  
Life Cycle ◽  
Energy Consumption ◽  
Energy Savings ◽  
Residential Building ◽  
Energy Performance ◽  
Simulation Tools ◽  
Energy Assessment ◽  
Energy Efficiency Improvement ◽  
The Difference ◽  
Reduction Of Energy Consumption

The reduction of energy consumption in the residential sector presents substantial potential through the implementation of energy efficiency improvement measures. Current trends involve the use of simulation tools which obtain the buildings’ energy performance to support the development of possible solutions to help reduce energy consumption. However, simulation tools demand considerable amounts of data regarding the buildings’ geometry, construction, and frequency of use. Additionally, the measured values tend to be different from the estimated values obtained with the use of energy simulation programs, an issue known as the ‘performance gap’. The proposed methodology provides a solution for both of the aforementioned problems, since the amount of data needed is considerably reduced and the results are calibrated using measured values. This new approach allows to find an optimal retrofitting project by life cycle energy assessment, in terms of cost and energy savings, for individual buildings as well as several blocks of buildings. Furthermore, the potential for implementation of the methodology is proven by obtaining a comprehensive energy rehabilitation plan for a residential building. The developed methodology provides highly accurate estimates of energy savings, directly linked to the buildings’ real energy needs, reducing the difference between the consumption measured and the predictions.

scholarly journals Building energy modeling at neighborhood scale

2020 ◽  
Vol 13 (7) ◽  
pp. 1353-1386 ◽  
Author(s):  
Guglielmina Mutani ◽  
Valeria Todeschi
Keyword(s):  
Energy Consumption ◽  
Energy Balance ◽  
Residential Buildings ◽  
Energy Performance ◽  
Average Error ◽  
Monthly Basis ◽  
Support Tool ◽  
Steady State Method ◽  
Consumption Data ◽  
Neighborhood Scale

Abstract The urban climate and outdoor air quality of cities that have a positive thermal balance depending on the thermal consumptions of buildings cause an increase of the urban heat island and global warming effects. The aim of this work has been to develop an energy balance using the energy consumption data of the district heating network. The here presented engineering energy model is at a neighborhood scale, and the energy-use results have been obtained from a heat balance of residential buildings, by means of a quasi-steady state method, on a monthly basis. The modeling approach also considers the characteristics of the urban context that may have a significant effect on its energy performance. The model includes a number of urban variables, such as solar exposition and thermal radiation lost to the sky of the built environment. This methodology was applied to thirty-three 1 km × 1 km meshes in the city of Turin, using the monthly energy consumption data of three consecutive heating seasons. The results showed that the model is accurate for old built areas; the average error is 10% for buildings constructed before 1970, while the error reaches 20% for newer buildings. The importance and originality of this study are related to the fact that the energy balance is applied at neighborhood scale and urban parameters are introduced with the support of a GIS tool. The resulting engineering models can be applied as a decision support tool for citizens, public administrations, and policy makers to evaluate the distribution of energy consumptions and the relative GHG emissions to promote a more sustainable urban environment. Future researches will be carried out with the aim of introducing other urban variables into the model, such as the canyon effect and the presence of vegetation.

scholarly journals Application of Life Cycle Energy Assessment in Residential Buildings: A Critical Review of Recent Trends

2020 ◽  
Vol 12 (1) ◽  
pp. 351 ◽  
Author(s):  
Hossein Omrany ◽  
Veronica Soebarto ◽  
Ehsan Sharifi ◽  
Ali Soltani
Keyword(s):  
Life Cycle ◽  
Energy Consumption ◽  
Energy Use ◽  
Residential Buildings ◽  
Current Trend ◽  
Energy Performance ◽  
Embodied Energy ◽  
System Boundary ◽  
Energy Assessment ◽  
Boundary Definition

Residential buildings are responsible for a considerable portion of energy consumption and greenhouse gas emissions worldwide. Correspondingly, many attempts have been made across the world to minimize energy consumption in this sector via regulations and building codes. The focus of these regulations has mainly been on reducing operational energy use, whereas the impacts of buildings’ embodied energy are frequently excluded. In recent years, there has been a growing interest in analyzing the energy performance of buildings via a life cycle energy assessment (LCEA) approach. The increasing amount of research has however caused the issue of a variation in results presented by LCEA studies, in which apparently similar case studies exhibited different results. This paper aims to identify the main sources of variation in LCEA studies by critically analyzing 26 studies representing 86 cases in 12 countries. The findings indicate that the current trend of LCEA application in residential buildings suffers from significant inaccuracy accruing from incomplete definitions of the system boundary, in tandem with the lack of consensus on measurements of operational and embodied energies. The findings call for a comprehensive framework through which system boundary definition for calculations of embodied and operational energies can be standardized.

scholarly journals An Occupant-Based Energy Consumption Model for User-Focused Design of Residential Buildings

2015 ◽  
Vol 137 (7) ◽  
Author(s):  
Toufic Zaraket ◽  
Bernard Yannou ◽  
Yann Leroy ◽  
Stéphanie Minel ◽  
Emilie Chapotot
Keyword(s):  
Energy Consumption ◽  
Residential Buildings ◽  
Energy Performance ◽  
Energy Simulation ◽  
Simulation Tools ◽  
Modeling Methodology ◽  
Management Processes ◽  
Proposed Model ◽  
Energy Consumption Model ◽  
Industrial Energy

Occupants' behavior exerts a significant influence on the energy performance of residential buildings. Industrial energy simulation tools often account for occupants' as monolithic elements with standard averaged energy consumption profiles. Predictions yielded by these tools can thus deviate dramatically from reality. This paper proposes an activity-based model for forecasting energy and water consumption of households and discusses how such an occupant-focused model may integrate a user-focused design of residential buildings. A literature review is first presented followed by a brief recall of the proposed modeling methodology and a sample of simulation results. The possible integration of the proposed model into the design and energy management processes of residential buildings is then demonstrated through a number of use cases.

scholarly journals Effects of the geometry of residential buildings with a sunspace on their energy performance

2019 ◽  
Vol 17 (1) ◽  
pp. 105-118
Author(s):  
Ana Vukadinovic ◽  
Jasmina Radosavljevic ◽  
Amelija Djordjevic ◽  
Nemanja Petrovic
Keyword(s):  
Energy Consumption ◽  
Aspect Ratio ◽  
Shape Factor ◽  
Residential Buildings ◽  
Dynamic Modelling ◽  
Building Design ◽  
Energy Performance ◽  
Total Consumption ◽  
Heating And Cooling ◽  
Heating Energy Consumption

The increase in energy consumption in building design and construction and the issues related to environmental protection have steered many current researchers toward examining the ways to reduce total CO2 emissions, which resulted in the development of various measures to increase energy efficiency. One measure for more cost-efficient and rational use of energy resources in individual residential buildings is the application of passive solar systems with a sunspace. This paper presents the effects of the shape factor of a residential building with a passive sunspace on the total consumption of heating and cooling energy. The total amount of energy required for building heating and cooling was calculated by means of dynamic modelling using EnergyPlus software. The simulations were run according to the meteorological parameters for the city of Nis. For simulation purposes, models of residential buildings with a passive sunspace and square- and rectangle-shaped floors were designed. The variations between the models include different building shape factor, floor geometry, surface area of the southern fa?ade, and glazing percentage, i.e. window-to-wall ratio (WWR). Examination of the models with WWR=20%, WWR=40%, and WWR=60% revealed that the elongated shape of a building with the aspect ratio of 2.25:1, with the longer side of the fa?ade facing south, is the most favourable in terms of heating energy consumption. For the same WWRs, the elongated shape of a building with the aspect ratio of 1.56:1, with the longer side of the fa?ade facing south, is the most favourable in terms of cooling energy consumption. As WWR increases, so does the amount of energy required to cool the building. The biggest increase in heating energy consumption was observed in buildings with the aspect ratio 1:2.25, with the shorter side facing south.

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