Building Energy Assessment Research Articles

Two-Stage Lifecycle Energy Optimization of Mid-Rise Residential Buildings with Building-Integrated Photovoltaic and Alternative Composite Façade Materials

Reducing the lifecycle energy use of buildings with renewable energy applications has become critical given the urgent need to decarbonize the building sector. Multi-objective optimizations have been widely applied to reduce the operational energy use of buildings, but limited studies concern the embodied or whole lifecycle energy use. Consequently, there are issues such as sub-optimal design solutions and unclear correlation between embodied and operational energy in the current building energy assessment. To address these gaps, this study integrates a multi-objective optimization method with building energy simulation and lifecycle assessment (LCA) to explore the optimal configuration of different building envelopes from a lifecycle perspective. Major contributions of the study include the integrated optimization which reflects the dynamics of the whole lifecycle energy use. Insights from the study reveal the optimal configuration of PV and composite building façades for different regions in sub-Saharan Africa. The lifecycle energy use for the optimized building design resulted in 24.59, 33.33, and 36.93% energy savings in Ghana, Burkina Faso, and Nigeria, respectively. Additionally, PV power generation can efficiently cover over 90% of the total building energy demand. This study provides valuable insights for building designers in sub-Saharan Africa and similar areas that minimize lifecycle energy demand.

Indoor Comfort, Thermal Indices, and Energy Assessment of Multi-Family Colonial Revival Style Buildings

Colonial Revival style residences have unique architectural features amongst others. They are common multi-family residences in the United States with no or limited information about their performance. The research purpose is to assess indoor comfort, energy performance, and thermal indices in multi-family Colonial Revival style residences. The research questions include (i) Do Colonial Revival style buildings perform better than other old buildings? (ii) Do the buildings consume additional electricity than typical and other old buildings? The research examined four case studies in Hartford County, Connecticut. The investigation explored comfort surveys, monitoring, collection of actual electricity usage, and assessed thermal indices using mathematical models. The average indoor temperature of 25.4 °C and relative humidity (RH) of 61.3% are reported. About 67% of the residents are thermally comfortable. The research noted significance between thermal sensation and other variables, excluding how occupants feel about the air movement. The average number of hours of temperature exceeds 28.0 °C and 30.0 °C marks for over 11.4% and 2.5% of the time, respectively, except in one of the buildings. The mean indoor temperatures are within the applicable bands of the adaptive comfort models. The averages of actual thermal sensation vote (TSV) ranged from 3.32 to 4.37 on a 7-point sensation scale. The mean neutral temperatures varied from 24.2–25.6 °C. The average monthly electricity bill is within the national average for residences in summer, excluding in August. The mean wet-bulb globe temperature (WBGT) of 21.1–22.3 °C and summer simmer index (SSI) of 30.1–32.4 °C are calculated as feasible bands for thermal indices in the buildings. The basements are more comfortable than other spaces within the case studies. The research outcomes can be used for future developments of Colonial Revival style and other similar buildings. The study recommends interventions such as retrofit to improve the performance of some existing Colonial Revival style buildings, especially the older ones that are less insulated with outdated equipment and appliances.

Assessing building energy performance and energy policy impact through the combined analysis of EPC data – The Italian case study of SIAPE

Energy Performance Certificates (EPCs) and EPC digital registers are key tools to evaluate different aspects of the building stock and its energy consumption. This paper presents several detailed energy performance evaluations on the Italian buildings based on a sample of over 2,000,000 EPCs extracted from the national EPC register (SIAPE), contributing to the definition of an updated energy performance baseline of the Italian building stock. This is the first work using the Italian EPC register to define such a baseline to the extent of the authors’ knowledge. Furthermore, combined analyses of EPC data were carried out to obtain information on the influence of the Italian energy regulations on building characteristics and on the effectiveness of energy strategy application for building renovation.This study underlines the relevance of EPC registers and how the combined analysis of EPC parameters can provide a large amount of useful information on several aspects of the building stock, allowing the monitoring of the impact of the Italian energy policy framework on buildings energy performance. Finally, based on these results, the paper supports public authorities and decision-makers in planning and developing future energy programs and identifying the best practices on the Italian territory.

A decision-making framework for life-cycle energy and seismic loss assessment of buildings

The integration of building seismic losses and environmental impacts is a key step toward the improvement of building design approaches accounting for resilience and sustainability in parallel. A decision-making framework including the life-cycle energy assessment and seismic loss estimation is proposed in this study in order to investigate the trade-offs between buildings’ environmental sustainability and reducing seismic loss. The framework includes a Pareto front analysis to reach a balance among the criteria. Building operational energy, embodied energy, seismic repair cost, and injuries were the performance metrics considered. The framework was applied to three reinforced concrete building designs including low- to high-rise buildings along with six exterior wall assemblies and four Window-to-Wall-Ratios. The contradictory trend among the performance metrics underlines the importance of merging these concepts for the development of the current building design methodologies. The hypervolume indicator was computed for each building’s Pareto front set to evaluate the quality of Pareto front design solutions. The results showed that compared to the 20-story building, the 2- and 12-story buildings have higher number of Pareto solution points and the solutions are of higher qualities in terms of diversity and proximity to the true Pareto front based on the hypervolume indicator solutions.

Improving the Efficiency of Maritime Infrastructures through a BIM-Based Building Energy Modelling Approach: A Case Study in Naples, Italy

Worldwide, the design, renovation, and sustainable management of port buildings play a crucial role for sustainability. In this framework, a computer simulation of a building’s thermal behaviour is an almost mandatory tool for making informed decisions. However, the development of a building energy model is a challenging task that could discourage its adoption. A possible solution would be to exploit an existing Building Information Modeling (BIM) model to automatically generate an accurate and flexible Building Energy Modeling (BEM) one. Such a method, which can substantially improve decision-making processes, still presents some issues and needs to be further investigated, as also detectable from the literature on the topic. In this framework, a novel workflow to extrapolate BIM data for energy simulation is proposed and analysed in this paper. Here, the BIM to BEM approach was tested as a useful tool for the maritime industry to improve the implementation of effective energy-saving measures. Specifically, in order to prove the capabilities of the proposed method, a maritime passenger station in Naples was chosen as case study and investigated by comparing different strategies to reduce the annual primary energy consumption. The optimal level of modelling detail required by a trustable building energy assessment was also investigated. By the proposed method, interesting primary energy savings (ranging from 24 to 41%) are achieved and CO2 emissions avoided (ranging from 16 to 34 tons CO2/year) for the investigated building, proving the potential of this approach. Definitely, this paper proves the validity of the proposed methodology and emphasizes its numerous benefits towards the achievements of the most modern sustainability standards.

An Evaluation Framework for Sustainable Plus Energy Neighbourhoods: Moving Beyond the Traditional Building Energy Assessment

There are international activities and on-going initiatives, particularly at the European level, to define what Positive Energy Districts should be, as the driving concept for the urban transition to a sustainable future. The first objective of the paper is to contribute to the on-going and lively debate about the definition of the notion of Sustainable Plus Energy Neighbourhood (SPEN), which highlights the multiple dimensions when talking about sustainability in districts moving beyond the traditional and strict building energy assessment. Based on a holistic methodology which ensures the consideration of the multidimensional nature and goals of SPEN, the paper outlines an evaluation framework. The evaluation framework defines the key performance indicators distributed in five categories that consider energy and power performance, GHG emissions, indoor environmental quality, smartness, flexibility, life cycle costs and social sustainability. This framework is designed to be implemented during integrated design processes aiming to select design options for a neighbourhood as well within during the operational phase for monitoring its performance. Further work will include the implementation and validation of the framework in four real-life positive energy neighbourhoods in different climate zones of Europe as part of syn.ikia H2020 project.

Changing the approach to energy compliance in residential buildings – re-imagining EPCs

As our need for energy information of buildings evolves, and the tools and methods at our disposal increase in scale and complexity, it is perhaps reasonable to expect a similar level of change in the way energy in buildings is assessed within national energy compliance frameworks. By comparing the available opportunities for building energy modelling with the current methodologies underlying Energy Performance Certificates, this study proposes future directions for standardised energy assessment of residential buildings and the impact this could have on different facets of energy policy. In carrying out this exercise, a number of criteria are proposed that could be used to appraise methodologies that align with future requirements of energy assessment, with two potential candidates for future energy assessment considered as part of this appraisal. An argument is thus proposed for better aligning future forms of standardised energy assessment with directions and requirements of future low-carbon energy policy.

Improvement of thermal comfort by hydraulic-driven ventilation device and space partition arrangement towards building energy saving

Horizontal space bears a great potential of rainwater, especially for the cities with an intense density of residential building in the middle and lower reaches of the Yangtze River (China). The rainwater collected on the roof has huge potential energy due to thealtitude differencefrom the ground, which belongs to the clean and renewable energy. Previous studies on the indoor passive ventilation strategies generally depend on the solar energy and the wind energy, resulting in failing to apply the potential energy of rainwater. Here, we proposed a novel hydraulic-driven ventilation device. This proposed device is regarded as a renewable energy supplier, since it can realize the indoor air movement by utilizing the potential energy of rainwater collected on the roof. Based on the experimental testing, we found that the hydraulic-driven ventilation device has a good capability, in terms of driving air movement. Furthermore, the numerical testing was carried out, to evaluate the indoor ventilation performances in two testing rooms of the study building integrated with the proposed ventilation system. The thermal comfort demander was taken into account, to optimize the building space partition arrangement. According to the building energy assessment tool, the integration of the hydraulic-driven ventilation device (i.e., renewable energy supplier) and the building space partition arrangement (i.e., thermal comfort demander), contributes to improving the building energy saving potentials by 46% and 43% for the periods of plum rain season and summer, respectively.

Performance assessment of different measured variables from onboard monitoring system to obtain the occupancy patterns of rooms in an office building

Considering the occupant behaviour as one of the most relevant matters that have an influence in the energy performance of buildings and also, one of the most relevant sources of the performance gap, the research work reported in this paper is focused on measuring the occupancy patterns as a variable that could contribute to overcome these problems. An in-depth work that analyses the suitability of different variables to obtain the occupancy patterns from measurements recorded by on-board monitoring systems is described. The indoor air temperature, the relative humidity, the CO2 concentration and the total electricity consumption measurements have been evaluated as occupancy indicators. The proposed approach has been applied to three rooms of an in-use office building. Said offices have different levels of occupancy and users with different habits. The study is based on selecting 32 months with four winters and four summers from a monitoring campaign from June 2013 to March 2019. The work schedule for the employees has been used as a reference to validate the results. This research demonstrates the capability to obtain occupancy patterns from measuring of the CO2 concentration and the total electricity consumption. The deviation between the occupancy patterns obtained from these variables and the reference schedule is under 10%, and it is lower for the rooms with larger occupancy rates. The proposed approach to obtain the occupancy patterns, together with new, smart and digitalised technologies, can contribute to catalyse the enhanced implementation of modelling techniques for building energy assessment and control.

Building Energy Performance Assessment Using an Easily Deployable Sensor Kit: Process, Risks, and Lessons Learned

In the building and construction sector, the mismatch between predicted and measured energy consumption is a well-known phenomenon called the performance gap. A promising approach to reduce the performance gap and thus improve the current building energy performance assessments are methods based on in-situ measurements. In this work, we present a building assessment process based on a novel, easily deployable wireless sensor kit. The basic sensor kit for building energy assessment presented in this study consists of a heating energy input node, several indoor temperature nodes, an outdoor temperature node, and a heat flux sensor. Specifically, the study outlines a medium-scale deployment of the sensor kit in eight occupied single-family homes in Switzerland and identifies the benefits of such an approach in the estimation of the overall heat loss coefficient and U-values. The findings of this study suggest that such sensor kits could be effectively used for rapid building performance assessment, and the paper concludes by outlining the potential benefits and implementation challenges of a larger scale study.

Opportunities and Limitations of Building Energy Performance Simulation Tools in the Early Stages of Building Design in the UK

This research investigates the use of Building Energy Performance Simulation (BEPS) tools in the early stages of building design in UK architectural practices with a particular focus on the barriers and opportunities to their effective application and further uptake. Two primary methods of investigation were undertaken; the first was a wide survey among UK architects and architectural practices, where the responses of 418 participants were electronically gathered and analysed. A deeper understanding of the issues was developed through an analysis of the process of low-energy building design using semi-structured interviews with six representatives of well-established architectural practices in the UK. The findings reveal that while there is an increasing understanding of the importance of BEPS involvement at the early design stages, there was limited evidence of actual early implementation of BEPS tools other than a few well known but specialised tools such as Passive House Planning Package (PHPP) which were used mainly for domestic energy performance evaluation. However, many practices surveyed showed interest in achieving higher standards than the “basic” regulatory backstops, which has resulted in Passive House and BREEAM seeing increasing use in domestic and non-domestic projects respectively. Although there has been a significant increase in the development and availability of tools and methodologies for assessing building energy performance our study shows that the focus for future research needs to be shifted from the “tool development” to looking at methods of implementing and using such tools in practice at the early design stages.

Koopman mode analysis on thermal data for building energy assessment

ABSTRACT Current approaches to thermal control and energy management in residential and office buildings rely on complex or high-dimensional thermal models. We provide a means to extract features from in-office thermal-data sensors which avoid the use of standard models. We develop these data-driven methods through the use of Koopman operator theory. We validate our resulting algorithms via analysing thermal data from a single thermal zone space. The particular advantage of the method is that it associates the temporal characteristics of control mechanisms with the corresponding spatial zones of influence. The methodology enables identification of spatial heating and cooling control modes directly from the data.

An efficient sensitivity analysis for energy performance of building envelope: A continuous derivative based approach

Within the framework of building energy assessment, this article proposes to use a derivative based sensitivity analysis of heat transfer models in a building envelope. Two, global and local, estimators are obtained at low computational cost, to evaluate the influence of the parameters on the model outputs. Ranking of these estimators values allows to reduce the number of model unknown parameters by excluding non-significant parameters. A comparison with variance and regression-based methods is carried out and the results highlight the satisfactory accuracy of the continuous-based approach. Moreover, for the carried investigations the approach is $100$ times faster compared to the variance-based methods. A case study applies the method to a real-world building wall. The sensitivity of the thermal loads to local or global variations of the wall thermal is investigated. Additionally, a case study of wall with window is analyzed.

Research Challenges and Advancements in the field of Sustainable Energy Technologies in the Built Environment

Inevitably, the 21st century has initiated a series of developments in the construction industry, leading to its digitalization and resulting in a series of innovative approaches and practices. At the same time, the construction industry, being one of the main global environment polluters, should fulfil well-established, as well as novel, sustainability requirements in order to evolve in harmony with the rising concerns on the availability of natural resources. This overview study aims to present the main developments, research, and scientific challenges in the field of sustainable construction, emphasizing the field of energy. The study aims to present a state-of-the-art scientific discussion on the sustainable built environment topic by analyzing cutting edge topics in the fields of building elements and whole building energy assessment, of indoor air quality and low carbon buildings, as well as on sustainable energy systems and smart buildings. The study also presents the state-of-the-art in existing tools which are adopted for the assessment of the sustainable built environment, including the use of digital tools and building information modelling for the energy assessment of the built environment, as well as the application of Life Cycle Assessment on building-related processes. Cross cutting issues related to the analysis of the building sector in the Industry 4.0 era, such as sustainability management topics and environmental geomatics are also discussed. The study concludes in those fields which will be of interest of the scientific community in the following years, towards achieving the goals of the sustainable development of the building sector.

An Integrated Microclimate-Energy Demand Simulation Method for the Assessment of Urban Districts

Rapid urbanization and densification processes are changing microclimatic environments in cities around the world. Even though previous studies have demonstrated the impact of urban microclimate on space cooling and heating demand, modeling tools employed to support the design process largely overlook microclimatic conditions in assessing building energy performance, making use of data from weather stations often located in rural areas. This paper presents a computational approach for the quantitative analysis of building energy demand at the district scale, including interdependent factors such as local air temperature, relative humidity and wind speed, diversity in building geometry and materials. The method, which couples the microclimate model ENVI-met and the district-scale energy simulation tool City Energy Analyst, is applied to a case study in Zurich, Switzerland, in order to analyze the energy performance of the area on a hot summer day. The study contributes to advance a coupling approach between a microclimate simulation and an energy tool at the district scale. The results showed that the coupled assessment approach can deal with complex interactions between geometry, building materials and energy systems. The consideration of local microclimatic conditions led to a 5% increase in the space cooling demand on the selected day, while the simulated peak cooling load for each building was 8% higher on average. The variation in the space cooling demand was found to be mainly due to an increase in latent cooling demand. Moreover, the coupling method allowed a detailed analysis of energy demand variation at the building level showing that, when considering the local climate patterns, the space cooling demand of the individual buildings varied between -5% and +14% on the selected day. The proposed method represents a next step to reflect the mutual interactions between buildings and microclimate in urban districts and aims at supporting decision-making in the design process.

Integration of a practical model to assess the local urban interactions in building energy simulation with a street canyon

To improve the prediction of the building’s energy performance, it has become necessary to evaluate their interactions with the urban microclimate. This study aims to propose an integrated model in the TRNSYS software with a simplified approach to assess building energy demand, including microclimate interactions on buildings. This model is based on thermoradiative and aeraulic modelling by considering the moisture transfer through the envelope. To evaluate the validity of this method, an urban canyon was modelled and compared with existing experimental results. The numerical results are close to the experimental observations with a mean absolute error of about 1°C for the outside surface temperature and a mean relative error of approximately 5%. The developed model has shown its potential in reducing an unexpected impact of interoperability when using several tools and to ensure shorter computation time compared to CFD calculations, with an accuracy satisfying the thermal and energy evaluation objectives.

A learning-based time-efficient framework for building energy performance evaluation

Recently, detailed building energy models are being widely used for building control assessments. When conducting such assessments, year-long simulations are usually deployed to cover as many building operation conditions as possible. However, year-long simulations can become computationally cumbersome, given the inherent nonlinearities of high-fidelity, detailed building models. In this paper, we propose a novel, time-efficient, and data-driven framework for selecting specific weather conditions when assessing building energy performance within a simulation environment. In the proposed framework, learning-based methodologies are used to group days of a performance assessment time window (usually a whole year) which are “similar” in terms of weather conditions (such as temperature, humidity, precipitation etc.) or contexts (such as “day of the week”, “weekday/weekend”, etc.) into different clusters. Following this, we select a finite number of “representative days” from each of these clusters, using which we try to understand the correlations between building performance and weather (or contexts) for each specific cluster. Subsequently, this knowledge is used to predict the building performance for the remaining “non-representative days”, and in turn estimate the overall annual energy performance of the whole building. We demonstrate the performance of the proposed framework on a varied suite of buildings across different geographical locations of the U.S. Results suggest that for practical purposes, our proposed approach can reduce the computational cost while maintaining considerable accuracy, compared to year-long simulations.

SENSITIVITY ANALYSIS OF BUILDING ENERGY PERFORMANCE BASED ON POLYNOMIAL CHAOS EXPANSION

ABSTRACT Global sensitivity analysis based on polynomial chaos expansion (PCE) shows interesting characteristics, including reduced simulation runs for computer models and high interpretability of sensitivity results. This paper explores these features of the PCE-based sensitivity analysis using an office building as a case study with the EnergyPlus simulation program. The results indicate that the predictive performance of PCE models is closely correlated with the stability of the sensitivity index, depending on sample number and expansion degree. Therefore, it is necessary to carefully assess model accuracy of PCE models and evaluate convergence of the sensitivity index when using PCE-based sensitivity analysis. It is also found that more simulation runs of building energy models are required for a higher expansion degree of the PCE model to obtain a reliable sensitivity index. A bootstrap technique with a random sample can be used to construct confidence intervals for sensitivity indicators in building energy assessment to provide robust sensitivity rankings.

The dual influence of the envelope on the thermal performance of conditioned and unconditioned buildings

Cities are progressively widening, incorporating rural and industrial zones and, at the same time, largest cities often need conversion of entire neighbourhoods. The transformation of large areas, through the introduction of energy-efficient buildings, quickly provides economic and social benefits. The current technologies for building energy-saving offer wide technical solutions range mainly developed for residential buildings. Nevertheless, the current literature lacks enough studies on envelope effectiveness in non-residential sectors, where indoor conditions are considerably different from residential.In this context, the paper aims at assessing the influence of five architectural characteristics on the thermal performances in a case study food-processing building. 576 building configurations are analyzed for six different intended use (0–24 °C) in conditioned and unconditioned scenarios. The performances of the different building configurations are expressed in terms of energy need (conditioned scenario) and thermal discomfort (unconditioned scenario). Results reveal that building thermal performance is connected to temperature ranges and the same building envelope characteristic can show positive or negative contribution according to the simulated scenario. Finally, for both scenarios, the most influential architectural characteristics have been identified and evaluated. Moreover, the paper proposes a methodology for building energy assessment for the transformation of existent industrial food-processing buildings in urban and suburban areas.

ENERGY ASSESSMENT OF URBAN BUILDINGS BASED ON GEOGRAPHIC INFORMATION SYSTEM

ABSTRACTUrban building energy analysis has attracted more attention as the population living in cities increases as does the associated energy consumption in urban environments. This paper proposes a systematic bottom-up method to conduct energy analysis and assess energy saving potentials by combining dynamic engineering-based energy models, machine learning models, and global sensitivity analysis within the GIS (Geographic Information System) environment for large-scale urban buildings. This method includes five steps: database construction of building parameters, automation of creating building models at the GIS environment, construction of machine learning models for building energy assessment, sensitivity analysis for choosing energy saving measures, and GIS visual evaluation of energy saving schemes. Campus buildings in Tianjin (China) are used as a case study to demonstrate the application of the method proposed in this research. The results indicate that the method proposed here can provide reliable and fast analysis to evaluate the energy performance of urban buildings and determine effective energy saving measures to reduce energy consumption of urban buildings. Moreover, the GIS-based analysis is very useful to both create energy models of buildings and display energy analysis results for urban buildings.