Building Energy Performance Assessment Research Articles

Recent advances in data mining and machine learning for enhanced building energy management

Due to the recent advancements in the Internet of Things and data science techniques, a wide range of studies have investigated the use of data mining (DM) and machine learning (ML) algorithms to enhance building energy management (BEM). However, different classes of DM and ML algorithms feature different mechanisms and capabilities, resulting in their distinct roles and performance in BEM. Appropriate integration of different categories of DM and ML algorithms in BEM is essential to promote their wide application and provide guidance for new topic areas. This study presents a literature review of the use of DM and ML techniques in key areas of BEM, including building performance evaluation, energy usage prediction, and demand flexibility optimization. The review categorizes DM and ML techniques into three main categories, including supervised DM, unsupervised DM, and reinforcement learning (RL). Unsupervised techniques are primarily used for building energy performance assessment, while supervised techniques are mainly employed for building performance benchmarking and energy usage prediction. RL has been utilized for optimal building control to improve efficiency, demand flexibility, and indoor thermal comfort. The strengths, shortcomings, and integration of these methods in terms of their applications in BEM are discussed, along with some suggestions for future research in this field.

Model simplification of geometry and facilities, for energy and indoor environment towards more reliable energy labelling

Reliable building energy and indoor climate performance assessment require adequate and often time-consuming modelling. Currently, energy performance certification (EPC) is carried out in Member States (MS) using simple steady-state tools. These tools simplify not only building geometry but also HVAC systems, boundary conditions, and building loads. These simplifications can cause the so-called “performance gap”, which is the difference between modelled prediction and actual operation. This creates a lack of trust in the EPCs and scepticism. This paper is scouting toward shifting to dynamic models of different detail levels, considering the zoning, heating and ventilation facilitie’s complexity. In the scope of this dynamic thermal simulation study, a residential multi-apartment building located in Denmark is investigated. The thermal zone simplification has 5 levels of complexity, from modelling each room as a thermal zone to the whole staircase as one thermal zone. The heating system was modelled as: i) ideal loads, ii) electrical radiators, iii) water radiators. Ventilation was modelled as i) zone ventilation, and ii) airflow network. Modelling results are evaluated for heat demand, thermal and atmospheric comfort.

A Statistical Analysis of Energy Consumption Survey of Public Buildings in a Hot Summer and Cold Winter Coastal Zone of China

Public buildings consume the largest proportion of total energy consumption and carbon dioxide emissions in the building sector of China. Enhancing building energy efficiency becomes a necessary way to reduce greenhouse gas emissions and energy waste. In this study, 10-year real data from 2000 buildings covering five different types of public buildings in a hot summer and cold winter zone in eastern coastal China were investigated to analyze energy-saving potential (ESP) and the impacts of various influencing factors on building energy performance. The concept of energy consumption limit (ECL) was proposed and used for identifying high energy-consuming buildings and the calculation of ESP. Hotels, shopping malls, and office buildings were the top three types of buildings with high ESP. ESP for the high energy-consuming buildings based on the benchmark limits was more than 18%, and that for three-star hotels and shopping malls was 51%. In addition, a correlation analysis between energy consumption and influencing factors was carried out, which laid the foundation for the development of building energy performance assessment and diagnosis tools.

An empirical model of a split-type inverter air conditioner for building energy simulation

The increasing adoption of air conditioning prompted by climate change and the fourth Industrial Revolution is poised to greatly influence the demand for energy consumption, especially in rapidly developing economies situated in the planet's hottest regions. The overwhelming majority of air conditioners (ACs) in use today around the globe are split systems, and the inverter technology is taking over the market for this kind of equipment, so it is extremely important for researchers to be able to simulate inverter air conditioners (IACs) behavior properly and demonstrate its energy efficiency benefit to help reduce energy consumption demand in the world. For energy performance assessment of buildings equipped with IACs, building energy simulation (BES) tools usually employ empirical models based on data provided by manufacturers to be able to simulate performance, however, even with the most updated standards in place, the data provided is not enough to provide a robust empirical model. The models available to predict IAC performance today are not well suited to be integrated with BES tools therefore this work aims to fulfill this gap by providing an empirical model built by adapting a methodology suggested by ASHRAE and based on 96 experimental tests variations to be able to simulate IAC performance more accurately, considering a wide range of temperature and humidity conditions and different compressor rotation speed values (30 Hz, 60 Hz and 90 Hz). All tests were carried out in a psychrometric calorimeter working according to an ISO standard and following the Air-Enthalpy Method. The paper provides a comprehensive breakdown of the calculation procedures used to ascertain and forecast total cooling capacity, sensible cooling capacity, and energy efficiency ratio, along with their associated uncertainties. This detailed explanation aims to facilitate the replication of the methodology by fellow researchers. The presented model exhibits a strong predictive capability for the tested IAC, boasting mean absolute errors of less than 5 % within an internal wet-bulb temperature range of 10–24 °C and an external dry-bulb temperature range of 25–40 °C. This level of accuracy makes it a suitable candidate for integration into various BES tools.

Smart Energy Performance Assessment Platform and next generation Energy Performance Certificate of buildings

After 10 years of track record, the current Energy Performance Certificate (EPC) schemes across the EU face several challenges which have led to not fully accomplish their initial objectives: lack of accuracy, a gap between theoretical and real consumption patterns, absence of proper protocols for inclusion of smart and novel technologies, little convergence across EU schemes, lack of trust in the market and very little user awareness related to energy efficiency. The objective of this paper is to show a holistic methodology for energy performance assessment and certification of buildings that can overcome the above mentioned challenges. The paper presents a Smart Energy Performance Assessment Platform which makes use of the most advanced techniques in dynamic and automated simulation modelling, big data analysis and machine learning, inverse modelling for the estimation of potential energy savings and economic viability check. The reliability, accuracy, user-friendliness and cost-effectiveness of the methodology is checked and validated through 15 case studies in 5 European countries. Additionally, a new useful, enriched and quite user-friendly Energy Performance Certificate format is presented which has been accepted by various target groups, i.e., building users and building related professionals, policy makers. This way, a universal web calculation platform is developed which, together with a new EPC template strongly support the EU goals for more reliable, uniform, and informative EPCs.

Impact of solar gain estimation on heat loss coefficient determination using in-situ data: Comparing co-heating test with B-splines integrated grey-box modelling

This study investigates the estimation uncertainties of grey-box models, with increased complexities of quantifying solar gain dynamics, in building energy performance assessment. The precision of solar gain estimation has been proven to be crucial for delivering a qualified grey-box model and achieving a better performance in predictive applications, e.g., model predictive control (MPC). Therefore, grey-box models that characterize solar gain dynamics more precisely are generally preferred. However, characterizing solar gain dynamics with more elaborated details might estimate solar gain dynamics more precisely but enlarge the uncertainties in accessing the buildings' overall energy performance, e.g., determining the buildings’ overall heat loss coefficient (HLC). Hence, this study aims to understand this potential risk. At first, four types of solar gain estimation approaches available for grey-box models are systematically summarized. The four grey-box models are applied to two datasets monitored on a full-scale lightweight building, under two scenarios of effective window distribution. The study reveals that enhancing the solar gain modelling in grey box models does not hamper a reliable HLC-determination in this case. Moreover, it was found that under certain conditions a more precise estimation of the solar gain can even reduce the uncertainty of the HLC-estimate via narrowing 95% confidence interval.

Comparison of Most Popular Buildings Performance Simulation Tools

A critical procedure in sustainable building design is the building energy performance assessment, which has significant implications for global energy consumption and climate change. This study compares three simulation software programs for a photovoltaic system on a building’s roof. The low-rise residential buildings in three East Mediterranean cities (Amman, Mafraq, and Aqaba) represent moderate drywarm, semiarid, and humid subtropical climate zones were compared using three simulation software programs (IES-VE, DesignBuilder, REVIT) for a typical building with PV on the roof and the second scenario without a PV system installed on the roof. This investigation aims to evaluate the shading effect of the PV system on a building’s roof structure by calculating the total electrical load required to maintain thermal comfort inside the building. The final results showed significant discrepancies between the three software for the base building design and the PV system on the roof, with a range of around 50 %. This highlights the importance of evaluating and calibrating different simulation tools and using them with a great deal of caution.

Downscaling of Hourly Climate Data for the Assessment of Building Energy Performance

In Italy, the calculation of the energy needs of buildings has been mainly based on quasi-steady state calculation procedures. Nowadays, the increasing interest in more detailed energy analysis for high-efficiency buildings requires more accurate calculation methods. In this work, starting from the hourly data of UNI 10349, the downscaling of a typical meteorological year was carried out by applying different mathematical and physical models for the main climate variables considered in the energy balance of a building to be used in dynamic simulation tools. All results were validated with one-minute measurements observed at the ENEA Research Centre in Rome, Italy. The results showed an MBE% of 0.008% and RMSE% of 0.114% using the interpolation spline method for the temperature, while, for the global horizontal irradiance, applying the novel sinusoidal–physical interpolation method showed an MBE% of −0.4% and an RMSE% of 31.8% for the 1 min observation data. In this paper, an easily implemented novel model for downscaling solar irradiance for all sky conditions that takes into account the physical aspects of atmospheric phenomena is presented.

Assessment of building energy performance integrated with solar PV: Towards a net zero energy residential campus in India

Building Applied Photovoltaics (BAPV) such as Roof-top Solar PV has gained significant attention in recent years for harnessing the untapped potential of renewable energy sources. However, rooftop PV poses hurdles of space restriction and shadowing in densely packed urban residential neighborhoods. This study aims to design and assess the feasibility of an integrated grid-connected Rooftop and Façade Building Integrated Photovoltaic (BIPV) for meeting the energy demand of residential buildings on an academic campus. Three distinctive groups of residential typologies have been investigated in this study, categorized based on built area and occupants’ past energy usage. Additionally, the variation in the measured Energy Performance index of the three different residential groups is illustrated to pave the path for the development of a typology-based residential energy benchmarking and labelling system. The Solar PV system has been designed for the maximum household energy demand recorded in CoVID-affected years due to high residential electricity usage in this period. The study showcases that integration of façade BIPV for low-rise residential buildings increases the system energy production to up to 62.5 % based on the utilized surface area for active PV. Furthermore, the Net Zero Energy Building (ZEB) potential for each typology has been achieved by integration of the proposed Solar PV, evaluated as a function of the Energy Performance Index (EPI) and Energy Generation Index (EGI). The designed nominal PV power of the proposed grid-connected plant is 5.6 MW, producing 7182 MWh annually, meeting the maximum residential energy demand in the studied academic campus in CoVID affected year.

Development of Building Energy Performance Benchmark for Hospitals

The energy consumption of existing buildings depends on their physical features, climatic conditions, and business activities, such as operating hours and occupancy characteristics. It is necessary to perform a fair assessment of building energy performance considering the business activities. It has become especially necessary to collect and manage information on business activities in hospitals since hospitals operate continuously throughout the year, treating patients and using various medical equipment. This study aimed to develop a benchmark that considers business activities and to perform building energy performance assessments in hospitals using the developed benchmark. Initially, the necessary data from hospitals for assessing energy performance and developing an energy benchmark were identified. Then, survey items regarding the business activities and energy consumption of buildings were designed, and a survey was conducted at 48 general hospitals. Secondly, multiple linear regression was used to identify and normalize the major business activities affecting energy use and to develop a benchmark for energy performance assessment. Thereafter, the Energy Efficiency Ratio (EER), the result of comparing the actual energy consumption with the benchmark, was used as an index for the energy performance assessment. Thirdly, additional general hospitals were surveyed to validate the benchmark. The EER of the additional surveyed hospitals was calculated with the developed benchmark. The Energy Use Intensity (EUI) and EER of buildings were reviewed, and analysis was performed to identify why some buildings had a similar EUI but a different EER. Finally, a method to improve the benchmark is presented, and the improved benchmark model is compared with the existing model.

A comparative analysis of building energy performance assessment on campus buildings (case study: Universitas Bangka Belitung)

Based on the sector, public buildings construction will become rapid development. Thus, good planning is needed to achieve a green and sustainable building. The necessity of well-planned campus buildings is required in establishing a new study program. UBB campus has a typical design and layout. It is apprehensive that the ineffective design concept in the construction will have a negative impact and waste energy. This study aims to evaluate the design of UBB campus building in terms of assessing the thermal and energy performance building on two building designs (Babel IV and Timah I). The design assessment employs the Rayman, CBE Thermal, OTTV calculation, and EDGE building. The analysis will be managed comparatively with several applications, to obtain significant factors. The results of this study shows that energy-efficient with a green concept can be applied in Bangka Belitung. However, the UBB campus building has not fulfilled the green building standards. In addition, it was found that the orientation and the WWR ratio can reduce the energy load on the building significantly.

Investigation of Energy Saving Using Building Information Modeling for Building Energy Performance in Office Building

With increased demand for energy and the simultaneous awareness of the environmental impact of building construction, there is an urgent need to consider the issue of sustainability in the design phase. This paper investigates the potential of Building Information Modeling (BIM) for building energy performance assessment, especially in Indonesia, and provides a framework and overview of the application of BIM related to building energy assessment. This paper used Revit software integrated with Green Building Studio as a BIM tool to analyze energy performance. The results showed that the best scenario for energy use reduction was shown by the last (8^th) scenario by combining all possible options covering a 12/5 operation schedule, high efficiency VAV HVAC type, efficient lighting, efficient plug load, instalment of control equipment daylight and occupants, Triple LoE for window glass and solar panels installation. The use of BIM in energy analysis is very useful to measure the amount of energy consumed at the design stage. The findings can be used as a guideline for the potential of BIM related to energy use analysis.

Assessment of the natural variability of cob buildings hygric and thermal properties at material scale: Influence of plants add-ons

This paper takes place in improving the energy performance assessment of cob buildings, by evaluating the variability of its hygrothermal properties at the material scale, related to the traditional construction process. For so, we proposed and analyzed data to handle the variability of the hygrothermal properties. The specimens were manufactured using a moulding method representative of on-site cob wall manufacturing process, for three plants species (hemp shiv, flax yarn and hay stalk) and three fibre content (0, 1% and 3%). Using non-destructive tests and statistical analysis, the random variability of cob composites hygrothermal properties (density, thermal conductivity, specific heat capacity, water-vapour permeability, moisture buffering value and sorption isotherms) was found as well as the variability distribution. It has been shown that the variability of properties is sensitive to the plant fibres specie and the fibre content. Using the variability indicators, it has been found on thermal conductivity, a low coefficient of variation of 2.88% for 1%-flax fibred mixture (lower than unfibred material) and a high one for 3%-hemp composites of 10.88%. The variability of sorption isotherms was usually found to be high at lower humidity loads. It has been shown that increasing the fibre22to make reading easier, we named as “fibre” on this paper, hemp shiv and hay stalk aggregates.content stabilizes the variability of properties. Moreover, some evolution trends of the variability according to mixes was proposed; two parameters were found: the first, either FCmax highlighting the fibre content for which the maximum of variability was achieved or FCmin for the opposite; the second is FCres highlighting the residual variability, for high fibre content. The distribution of properties were found to be generally centred.

Energy performance assessment of passive buildings in future climatic scenarios: the case of study of the childcare centre in Putignano (Bari, Italy)

The building sector is a primary target for GreenHouse Gas emissions mitigation efforts, as it accounts for 36% of final energy use. The most effective mitigation strategies include the energy retrofit of the existing building stock. Among existing buildings, particular attention should be paid to school buildings, which are among the most diffuse public buildings in Europe, most of them built decades ago, with a resulting high potential in terms of refurbishment effectiveness. Moreover, schools cover a social function and require high levels of indoor environmental quality. In this field, the research activity is intense, but retrofit strategies are still conceived considering historical weather data, which could not represent correctly present and future climate patterns, reducing the retrofit effectiveness. In this work, an energy retrofit to “Passivhaus standard” of a childcare centre located in the Mediterranean area is analysed through dynamic simulations. A post-retrofit building model is simulated using Typical Meteorological Year (TMY) and compared with the ones simulated in future weather scenarios, created using the morphing method. The analyses aim to assess if the technical solutions currently adopted on the basis of the TMY will lead to acceptable energy performance in future decades. Furthermore, a sensitivity analysis of different design solutions is performed, aiming to assess their effectiveness in future weather conditions.

A structured method to define goals when developing a building energy performance assessment method in a legislative framework

To boost the energy performance of buildings, the EU has established a legislative framework including the Energy Performance of Buildings Directive (EPBD). Through this document, EU state members are incentivized to set up a Building Energy performance Assessment Method (BEAM), tailored to the specific needs of the country. There is no standard definition for the energy performance of a building. Since the options are numerous, it is important for the policymaker to define the goals of their specific BEAM first, before developing the BEAM itself. The definition of these goals is a subjective matter and can differ when asked to different organizations in the building sector. To comprehend the desires and perspectives from each different group, a structured overview of the goals that are important for the specific region is needed. For this paper, a method was developed to provide this structured overview and was tested on the legislative energy performance of buildings (EPB) framework of Flanders, Belgium. The Flemish framework was initiated in 2006 and is still in action today. The method consists of two steps. In the first step, a multi-level tree structure for goal mapping based on the Goal Breakdown Structure (GBS) was developed. The main goal, reducing global warming, is on top of the tree structure, which then subdivides into many sub-goals on different levels. An example of a goal on the lowest level of the structure could be the insulation level of the walls. In the second step, prominent stakeholders in the Flemish building industry, including policymakers, researchers, manufacturers, contractors and building owners, were surveyed to capture their expectations from a BEAM and to query whether the current BEAM corresponds with those expectations. The goal of this survey was to receive qualitative, not quantitative input from the stakeholders. In total, 33 respondents completed the survey. The survey results showed that, in general, the desired goals have not changed substantially compared to the pre-set goals in 2006. Trias Energetica is still the preferred guideline for the decision-making process of the building owner, although its absolute power has decreased slightly and seems to be more prone to the conditions. The current indicator for the overall energy needs (E level) is still strongly preferred, while the recently introduced S level (assessment of the envelope) attracts mixed feelings in terms of usefulness to the entire EPB framework. The overheating indicator receives the most critique for not being accurate enough due to the simplified, single zone BEAM

Validation of the simplified heat conduction model of EN ISO 52016-1

The issue of improving the building energy efficiency led to the development of calculation methods for the building energy performance assessment. To overcome the low accessibility to detailed input data, the recently introduced EN ISO 52016-1 hourly method is based on assumptions and simplifications chosen to allow a sufficient accuracy in the outcomes with a low amount of input data. Among these assumptions, a simplified mass distribution in the envelope components is considered. In the present work, the hypothesis of the simplified heat conduction model introduced by the EN ISO 52016-1 technical standard and an improved solution provided by its Italian National Annex were evaluated. In particular, the accuracy in the prediction of the internal surface temperature was assessed in comparison with a detailed finite difference conduction algorithm. The validation was performed for 5 opaque component test cases, covering a wide range of areal heat capacity values, by considering both internal and external thermal constraints (e.g. variation of the air temperature). For the structures and boundary conditions considered, results reveal that the standard algorithm allows to predict the internal surface temperatures with a valuable level of accuracy compared to the finite difference algorithm.

Accuracy of Simplified Modelling Assumptions on External and Internal Driving Forces in the Building Energy Performance Simulation

The recently issued EN ISO 52016-1 technical standard provides a new simplified dynamic method for the building energy performance assessment. Since an extensive validation of the EN ISO 52016-1 hourly method is still missing, the present work investigates the effect of the main modelling assumptions—related to the heat balance on the outdoor and the indoor envelope surfaces—on the building thermal behaviour. The model validation was carried out by assessing the accuracy variation consequent to the application of the EN ISO 52016-1 modelling assumptions to a detailed dynamic calculation tool (EnergyPlus). To guarantee a general validity of the outcomes, two buildings, two levels of thermal insulation, and two Italian climatic zones were considered, for a total of eight case studies. To explore different applications of the standard method, the analysis was performed both under a free-floating condition—to evaluate the accuracy of the model in predicting the indoor operative temperatures—and to assess the annual energy needs for space heating and cooling. Results show that the assumptions related to the definition of the external convective and the shortwave (solar) radiation heat transfer lead to non-negligible inaccuracies in the EN ISO 52016-1 hourly model.

Analysing the future energy performance of residential buildings in the most populated Italian climatic zone: A study of climate change impacts

There is growing concern that global warming will change the building’s performance pattern in the future. This paper investigates the effects of climate changes on the heating and cooling energy demand, the overall energy performance and the overheating risk of typical residential buildings (existing and refurbished) in the biggest city of the most populated Italian climatic zone, Milan. The widely used morphing methodology was adapted for creating future weather data for different scenarios. Energy performance analysis was carried out using dynamic simulation for the near term (2021–2040) and the long term (2081–2099) periods. The results show decreases in heating energy demand up to 30.9%, intense increases in cooling energy demand, up to 255.1% and significant increases of overheating risk up to 155%. In addition, the effect of refurbishment on each parameter is also analysed and reported. The research demonstrates that climate change causes a paradigm shift in the building energy performance, while the magnitude of climate change impact is not equal for different building types, time periods, insulation levels, and future weather scenarios. Therefore, climate change must be considered for future energy performance assessment of buildings.

Measuring the heat transfer coefficient (HTC) in buildings: A stakeholder's survey

The heat transfer coefficient (HTC) is a very important factor influencing the energy performance of a building. Recent studies have shown the importance of on-site measurements of the HTC in reducing the performance gap in buildings. However, its measurement setup and calculation procedures are known to be intense and complex. Due to this, many stakeholders in the building industry find it impractical and insufficient for their needs. This paper presents the results of an international survey that targets such stakeholders with the aim to get their perspectives on HTC measurements on-site. Several stakeholders from 14 countries in Europe participated in the survey. The survey is categorized into four parts: a) basic data about the participants, b) their interest in methods for measured energy performance, c) their views on the characteristics of such a methodology and d) their concerns and opportunities. The results reveal that the stakeholders are highly interested in measuring the HTC on-site. The results also provide interesting insights on the aspects relevant for them and their customers. In particular, we elaborate on their perspective on the time to conduct the measurement, the cost of the setup, the measurement duration and the acceptable error. The assimilated understanding from the survey will help the building and the construction industry to identify opportunities for a progressive assessment campaign involving on-site measurements. This study is part of the International Energy Agency's Energy in Buildings and Communities Programme (IEA EBC) Annex-71 project titled ‘Building energy performance assessment based on optimized in-situ measurements’.

Energy Performance Assessment Framework for Residential Buildings in Saudi Arabia

The residential sector consumes about 50% of the electricity produced from fossil fuels in Saudi Arabia. The residential energy demand is increasing. Moreover, a simple building energy performance assessment framework is not available for hot arid developing countries. This research proposes an energy performance assessment framework for residential buildings in hot and arid regions, which focuses on three performance criteria: operational energy, GHG emissions, and cost. The proposed framework has been applied to three types of residential buildings, i.e., detached, attached, and low-rise apartments, in five geographical regions of Saudi Arabia. Design Builder® was used to simulate the energy demand in buildings over a whole year. Four types of efficiency improvement interventions, including double-glazed windowpanes, triple-glazed windowpanes, LED lighting, and split air conditioners, were introduced in 12 combinations. Overall, 180 simulations were performed which are based on 12 intervention combinations, three building types, and five regions. Three performance criteria were evaluated for each simulation and then aggregated using a multi-criteria decision analysis method to identify the best intervention strategy for a given building type and a geographical region in Saudi Arabia. Each building type with interventions consumes higher energy in the western, central, and eastern regions and consumes a lesser amount of energy in the southern and northern regions. The proposed framework is helpful for long-term planning of the residential sector.