Building Performance Simulation Software Research Articles

THERMAL IDENTIFICATION BASED ON BUILDING ENVELOPE, SHAPE & ORIENTATION USING SEFAIRA SIMULATION METHOD. (CASE STUDY OF BUILDING B, ARCHITECTURE DEPARTMENT, UNIVERSITY OF LAMPUNG)

The building envelope, which serves as the boundary layer between the interior and exterior, plays a crucial role in regulating heat exchange. The shape of the building also impacts heat distribution and airflow within and around the structure. The orientation of the building, particularly in relation to the sun, determines how much solar radiation it receives, directly affecting the building's thermal load.Using Sefaira, a building performance simulation software, researchers can visualize and optimize these thermal aspects. This simulation allows them to experiment with various scenarios related to the building envelope, shape, and orientation to achieve ideal thermal conditions, which are not only comfortable for occupants but also energy-efficient.The findings of this research are expected to provide new insights into sustainable architectural design, especially in tropical regions like Lampung. By understanding and applying the correct thermal principles, buildings can be designed to minimize energy usage for cooling or heating, supporting efforts to reduce the impacts of climate change

Development of Prefabricated Additional Insulation Elements for the Renovation of High-Rise Apartment Buildings

Prefabricated additional insulation elements have demonstrated success in renovating up to 5-storey apartment buildings. However, the unique challenges posed by high-rise buildings necessitate a closer examination of installation and long-term performance. In this study, we developed an additional insulation element specifically tailored for renovating high-rise apartment buildings and analysed its hygrothermal performance. To test the performance of the insulation elements, we installed a prototype and measured its performance at critical points along the external envelope. We calibrated a calculation model and applied building performance simulation software to explore various combinations of prefabricated elements. Our goal was to compare the associated risks and the key hygrothermal properties of these different material combinations within the insulation element. Critical points between the insulation layer and the wind barrier, as well as between the surface of the existing concrete panel wall and the vapour control layer of the additionally insulated exterior wall were analysed. The study's results indicate that the thermal resistance and water vapour permeability of the wind barrier layer, and the presence of an appropriate vapour control layer primarily influence the performance and moisture dry-out of a structure. Additionally, the study results indicate that the weather component has a higher impact than in lower buildings as the wind-driven rain loads are considerably higher in the upper parts of the high-rise buildings. The initial moisture (w = 110 kg/m3 at the height of the 9th storey and w = 117 kg/m3 at the height of the 16th storey) dry-out can last more than 3 years depending on the building type and materials used. This study underscores the importance of tailored solutions and vigilant moisture safety management in high-rise apartment building renovations, particularly when utilizing prefabricated additional insulation elements.

Assessment of HVAC Performance and Savings in Office Buildings Using Data-Driven Method

Enhancing energy efficiency within the building sector is imperative to curbing energy losses, given that this sector alone contributes to over 34% of global energy consumption. Employing a building management system, along with its regular updates, presents a strategic avenue to decrease energy usage, enhance building energy efficiency, and more. Tailored control strategies, aligned with the unique characteristics and usage patterns of each building, are essential for achieving energy savings. This article presents an evaluation of HVAC system efficiency in office buildings, utilizing a data-driven approach coupled with simulations conducted in building performance simulation software. The research explores the control strategy of an office building equipped with a constant air volume HVAC system, featuring a regularly controlled air handling unit. The objective is to boost energy efficiency while striking a balance between occupant comfort and energy consumption. The findings indicate that by analyzing measured data and adjusting the configurable parameters, the energy consumption of buildings can be significantly reduced. The close monitoring of indoor parameters by building operators and making corresponding adjustments to the HVAC system can yield energy savings of up to 16%. Leveraging these insights, this paper suggests integrating data-driven and dynamic simulation methods into building management system models to optimize HVAC systems, enhance energy efficiency, and advance ambitious carbon neutrality objectives.

A hybrid learning approach to model the diversity of window-opening behavior

The diverse window-opening behaviors of individuals can result in significant differences in indoor thermal environments, air quality, and energy utilization. However, the majority of existing studies focus on constructing an average window operation model, thus overlooking the diversity of behaviors. Current methods for addressing behavioral diversity face challenges with integration into building performance simulation software and are highly dependent on data scale. To address these limitations, this study proposes a novel approach that combines unsupervised learning (K-Means) and supervised learning (Light Gradient Boosting Machine, LightGBM) for modeling the diverse window-opening behaviors. Furthermore, the SHapley Additive exPlanations (SHAP) was employed to interpret the predictive model. This study yielded four key findings: 1) There were 12 different window-opening behavior patterns. Interestingly, 65 % of the residents’ window-opening behaviors were not influenced by environmental factors but were instead a matter of personal habit. 2) Using random sampling to divide the dataset may pose a risk of data leakage. The time series cross-validation method is more suitable for evaluating the performance of the window state prediction model. 3) Under the time series sampling strategy, the LightGBM model incorporating behavioral diversity improved the prediction accuracy by 1.3%–10.4 % compared to the standalone LightGBM model. Notably, when the daily average window opening time was used as a clustering feature in the LightGBM model (Cluster(T)-LightGBM), the accuracy reached 87.1 %. 4) The SHAP feature analysis highlighted high-intensity window-opening categories, outdoor temperature, and indoor CO2 concentration as the most pivotal predictors.

The Effect of Parametric Patterned Façade Variations on Daylight Quality, Visual Comfort, and Daylight Performance in Architecture Studio-Based Tutoring

Parametric design influences on building envelope design are exponentially increasing in the current era due to the dominance of computational design on architectural outcomes. The composition of the building envelope’s patterns, shape, size, and distribution of the perforations can affect the efficiency of daylighting within the space; daylight quality, visual comfort, and daylight performance. Through the manipulation of the daylighting patterns, a balance between illuminance and glare control is created. This research study aims to analyze and evaluate the effect of different parametric patterns integration on daylighting in “Architecture Studio-based” tutoring through the distribution of perforation on façade openings, percentage of perforation, and perforation size in a hot-dry climate. The analysis is conducted through building performance simulation software (Climate Studio). The research concludes that the “Triangles Parametric Pattern” among all the tested patterns, achieves the highest performance in compliance with the recommended thresholds of daylight quality, visual comfort, and daylight performance metrics within the studio space compared to other parametric patterns and the base case model. The implications of such an experiment inform designers to categorize daylight performance while selecting patterns in window design as part of façade design.

Validating a Building Performance Simulation Model of a naturally ventilated Double Skin Facade

Double Skin Facades (DSF) are regaining popularity as a way to increase the climate resilience of buildings. Building Performance Simulation (BPS) is commonly used for their assessment, but modelling DSFs with BPS is challenging due to their complex thermophysical behaviour. Several research works have evaluated the capabilities and limitations of BPS for modelling specific DSF configurations. This work presents a validation study based on experimental data from a full-scale naturally ventilated double-skin façade, compared against results from the BPS software IDA-ICE. The study found that in periods with low solar irradiation, the different modelling strategies had a minor influence on the results, with a high agreement between measurements and simulation. In contrast, periods with solar irradiation showed a higher sensitivity to the modelling strategy, with more significant deviations from the measurement results.

Development of a BLOCK zonal model in a BPS software to predict thermal stratification and air flows

An excellent way to obtain a detailed description of the air flows and temperature field in a zone is to perform accurate Computational Fluid Dynamics (CFD) simulations. Unfortunately, this is often prohibitive due to the powerful resources that are required, and the large computational times. As a consequence, several intermediate models between CFD and the standard well-mixed models have been proposed over the years. These are known as zonal models, and they aim at delivering sufficiently accurate predictions of the thermal comfort in a room, for long periods (months or even years), and with substantially shorter computational times. However, none of these models has yet been implemented in a building performance simulation (BPS) tool. In this work, we have developed and implemented a BLOCK zonal model [1,2] within the IDA ICE (BPS) software. A multi-node 1D model for the prediction of vertical temperature gradients is used, together with flow element theory and an appropriate algorithm for the estimation of view-factors in non-convex geometries with obstacles. The paper presents the theoretical background of the model along with advice on its range of applicability. Finally, the model is validated against several test cases, showing its suitability in predicting the thermal stratification.

A comparison of six metamodeling techniques applied to multi building performance vectors prediction on gymnasiums under multiple climate conditions

Building performance simulation (BPS) is essential for testing energy demand and indoor environment quality of different building designs. However, software for BPS is computationally intensive and impractical to run thousands even millions of simulations for performance analysis and optimization. Especially for the large space buildings, which usually have complex forms and high energy consumption. The computational problem could be overcome by the adoption of metamodels. Most correlational research focuses on single performance prediction of a particular building, which makes the model less robust when applied to multi vectors prediction for different buildings under multiple weather conditions. This paper leveraged six metamodels, which include recurrent deterministic policy gradient (RDPG), asynchronous advantage actor-critic (A3C), long short-term memory (LSTM), convolution neural network (CNN), artificial neural network (ANN) and support vector regression (SVR), to predict hourly-based multi performance vectors of gymnasiums under various design parameters and multiple weather conditions. Six metamodels are trained and tested on a large scale of datasets simulated by EnergyPlus over four gymnasium cases in different cities of China. The accuracy, efficiency, ease-of-use, robustness and interpretability of the models are investigated. To conduct a fair and detailed comparison, a methodological approach using grid searches for model settings selection assisted by sensitivity analysis is pursued. Principal component analysis (PCA) is also adopted to interpret the work process of the metamodels. The comparison showed that the RDPG model provides the most accurate prediction results with R2 converges at 0.993, 0.982 and 0.941 for energy, temperature and CO2, respectively. LSTM model is more efficient than RDPG, and suitable for users who need emphasis on both time and accuracy. ANN is suitable for users with limited time and require models of ease-of-use and robustness. SVR and ANN could be used for the automatically co-simulation with BPS software. In future research, the influence of occupant behavior also should be investigated.

Thermal effects of dew on cool roofs and conventional roofs in building performance simulations

This paper presents a numerical investigation of dew formation on the roofs of buildings, and its influence on building thermal and energy performance. A new semi-analytical model was developed to evaluate the effects of rooftop dew, including the release/absorption of latent heat due to condensation/evaporation, the variation of apparent thermal emittance of the roof upper surface, and the dew runoff characterised based on laboratory experiments. A set of case study simulations was carried out by implementing the rooftop dew model in the building performance simulation (BPS) software EnergyPlus. Through its impact on roof top surface temperature, dew was found to significantly influence predictions of benefits and penalties of a ‘cool roof’ versus a bare metal roof. When dew effects were neglected in the simulations, the electricity savings attributed to the cool roof were over-predicted by between 39 % and 204 %, however, the gas heating ‘penalty’ of using a cool roof was over-predicted by 266 % to 362 %. Results from this study demonstrate that the thermal effects of dew on roofs can be important in BPS studies, and the model that is presented provides a relatively simple means by which to include such effects in simulations.

The Investigation of Natural Light Level and Distribution Based on Opening Orientation (Case Studies: Laboratory in Educational Building)

This research investigates the level and distribution of natural lighting based on the orientation of the openings in the laboratory room in the educational building at a university in Depok, West Java, Indonesia. The building was built using a green building approach. This building has several functions, two of which are the Basic Chemistry Lab and Biomedical Lab, which are located on the 8th floor of the educational building. This study addresses the questions, which laboratory room has the highest level of natural light in terms of the orientation of its openings? How is the distribution of natural lighting in these two laboratory rooms? On-site measurement was conducted to determine the natural light levels in laboratory rooms and building performance simulation software was used to investigate the distribution of natural lighting throughout the room. The results show that the level of natural lighting in the Basic Chemistry Lab (openings on the north side) and in the Biomedical Lab (openings on the south side) is similar, depends on the time and the sun position. The distribution of natural lighting in both laboratory rooms is not evenly distributed. To meet lighting needs, it is therefore the use of the distribution of natural light in the two rooms that needs to be adjusted.

Modelling method for air-conditioning usage behavior in multi-occupant office space based on group decision-making strategy

Occupant behavior largely influence the energy use within buildings. In the multi-occupant office, occupant behavior is affected by individual preference as well as the interaction among occupants, and yet no suitable model is available to precisely reflect the behavior characteristics. This paper proposed and introduced a method for innovative multi-occupant air-conditioning (AC) usage behavior modelling in a multi-occupant office, which used intuitionistic fuzzy preference relationship to describe individual behavior intention and a hierarchical structure to reflect the social relationship among multiple occupants through subjective evaluation method. The group decision-making process combined the individual behavior intention and the weights of occupants using the analytic hierarchy process. Then, the AC usage behavior of a multi-occupant office was simulated by integrating the multi-occupant model into designer's simulation toolkit (DeST) building performance simulation software. The results of conducted analysis of a single office with multi-occupant showed that the proposed multi-occupant modelling method could quantitatively characterize the group relationships and AC usage behavior patterns. The absolute errors for the total AC operation time and frequency of the start-up periods of AC between the simulation and measurement results were only 2.7% and 2.0%, respectively. Thus, the proposed multi-occupant modelling method could realize a relatively accurate simulation of the multi-occupant behavior.

Numerical Feasibility Study of Self-Regulating Radiant Ceiling in Combination with Diffuse Ceiling Ventilation

A focus on indoor comfort and tightening targets for energy savings in buildings presents new opportunities for heating, ventilation, and air-conditioning products (HVAC). This paper presents a novel comfort solution that integrates a suspended radiant ceiling with diffuse ventilation, dubbed HVACeiling. In combination with the concrete slab, the HVACeiling has the potential to provide thermal comfort with minimal temperature offset, which supports operation of the heating and cooling system at temperatures very close to the room comfort temperature. The paper presents a parametric numerical study of the concept in a simplified two-pipe layout with fixed flow and fixed temperatures. First, the analysis was focused on different internal and solar loads, heat losses, and climatic locations with the aim of assessing the potential of self-regulation, i.e., no active controls, thermal comfort, ability to reduce peak loads and the consequential building design considerations. Secondly, the purpose was to analyse the concept in a generic office building with five offices and one meeting room and compare it to other HVAC solutions. The whole-year analyses of heating, cooling, energy performance, and thermal comfort were done using the building performance simulation software IDA ICE. It was found that it was possible to create thermal comfort in Paris, Munich, and Copenhagen with water circulating constantly with fixed temperatures of 20–24 °C without controls and with window sizes from 15 to 30% of the floor area. The studies showed that the HVACeiling reduced the operative peak temperatures on the warmest days in comparison with a standard radiant ceiling with mixing ventilation by 1 K. Compared to all-air solutions, the HVACeiling reduced the yearly energy consumption by 20–30% and the peak power in summer up to 69%. This study indicates that thermal comfort is achievable in a European context even at very small temperature offsets, which supports the use of more renewable energy sources.

Co-simulation of dynamic underground heat transfer with building energy modeling based on equivalent slab method

Ground-coupled building envelopes contribute to up to 45% of total building heat loss. Dynamic simulation of the thermal process of the building-ground structure is essential for whole-year building energy simulations and evaluations. There exist various types of underground heat transfer models, while the adoption of dynamic underground heat transfer models in building energy simulation software is quite limited because of accuracy or computational efficiency issues. To fill this gap, this research proposes a novel co-simulation framework for dynamic underground heat transfer with building energy models. An XGB regression model was developed for the calculation of the heat response coefficient of building-ground structures, based on which an equivalent slab model is proposed and integrated with the general building energy models. The proposed co-simulation model was validated using the detailed 3-dimensional finite difference method. It can be concluded from the validation results that the simulation errors of the inner surface temperature of ground-coupled envelopes do not exceed 0.6℃, while the computational speed is improved by 4000–20000 times. The proposed model was integrated into the building performance simulation software DeST for the whole-year dynamic simulation of building-ground structures.

Indoor thermal climate after energy efficiency measures of a residential building in a sub-Arctic region: Comparing ANSYS CFX and IDA ICE methods

A residential building which had been subjected to an energy efficiency measures study had its indoor thermal climate investigated using two software approaches to understand how each approach would predict the outcome, using the predicted percentage of dissatisfied (PPD). The computational fluid dynamics software (ANSYS CFX) and the building performance simulation (BPS) software (IDA ICE) were used to simulate the indoor thermal climate before and after the measures. The measures included additional insulation and changing the ventilation system. The results showed a difference in how the software packages handled the thermal radiation. The difference was also because CFX could calculate the indoor thermal climate of the whole interior. While the PPD values could remain similar between the CFX solutions, the area with dissatisfaction in the apartment was decreased when the building envelope was improved. These changes gave an improvement for the CFX solutions, which was not possible to predict with IDA ICE because only the central node was visible. The user should be aware of the shortcomings of BPS and building energy simulation software when evaluating the indoor thermal climate to predict changes. A coupling between BPS and CFX software should be considered when new measures or significant changes are planned.

Modelling of rooms with active chilled beams

ABSTRACT Active chilled beams (ACBs) are often modelled as generic cooling devices. Due to induction, the air flow discharged from an ACB is several times higher than supplied from the air handling unit, and due to its design, it affects the temperature of the ceiling to a greater extent than an arbitrary cooling device. This paper investigates the impact of taking these features into account when simulating air and operative temperature in a room equipped with an ACB. The building performance simulation software IDA ICE is used for analysis and the simulations are compared with full-scale experiments. The main findings are that simulations which take into account the features mentioned above correspond more closely with measurements. If designing for a certain operative temperature, this reduces the required design cooling capacity. Although negligible in many applications, the magnitude of this reduction is 9% with high-temperature cooling.

Development and Performance Assessment of Prefabricated Insulation Elements for Deep Energy Renovation of Apartment Buildings

A need for the refurbishment and renewal of the existing building stock has been in focus for many decades, principally because of excessive global energy consumption and pollution. This paper presents a methodology and the results of analysis of choices of realizable sets of timber frame prefabricated insulation elements for major renovation of apartment buildings. Numerous combinations of elements with different characteristics were analyzed by applying measurements, interviews, and building performance simulation software, and thereupon their performance, installation eligibility, and concurrent cost levels were compared. Mineral wool board with a special wind barrier facing was found to be the best material as a wind barrier from the perspective of hygrothermal performance. An air and vapor barrier should have sufficient vapor permeability to allow dry-out of constructional moisture. It is possible to renovate apartment buildings to meet the nZEB energy performance requirements and their moisture safety can be guaranteed without paying high relative difference cost. Calculations showed that the global cost was lower for solutions with some mold growth risk. Great care is needed when decreasing costs without simultaneous hygrothermal analyses. The facade cladding was found to have the highest influence on the initial cost of the prefabricated insulation element.

Development of prefabricated insulation elements for buildings with aerated autoclaved concrete walls

An extensive need for the refurbishment and renewal of existing building stock has been the focus of consideration for many decades, principally because of the high global energy consumption and pollution levels. This paper presents the results of the analysis of certain sets of timber frame prefabricated insulation elements for the major renovation of an apartment building. The hygrothermal measurements were taken, and a series of combinations with elements were analysed using building performance simulation software to compare the main hygrothermal properties. The critical initial moisture content for the surface section of the aerated autoclaved concrete (AAC) panel is w = 65 kg/m3 at a depth of 15 mm and w = 39 kg/m3 at a depth of 70 mm. The results showed that before the design and installation of insulation elements, thorough hygrothermal analysis of the original external envelope, with actual climatic conditions and moisture loads, must be realized.

Dynamic evaluations of heat pump and micro combined heat and power systems using the hardware-in-the-loop approach

The seasonal coefficient of performance (SCOP) of a heat pump is nowadays determined according to standards on the basis of steady-state measurements in laboratories. Monitoring data from field tests show non-negligible deviations regarding SCOPs compared to values identified according to state-of-the-art standards. Observed deviations are partly due to neglecting instationary effects during momentary efficiency measurements of standards. To counter this problem, three institutes have collaborated on developing a novel dynamic testing procedure making use of the hardware-in-the-loop (HiL) concept. Furthermore, the control volume for the energy balance is extended to the whole system including the energy conversion system's controller. The energy conversion system is coupled via adequate test benches to a real-time building performance simulation. In order to evaluate the annual efficiency according to the HiL approach, the experiments demand a feasible time frame. For this purpose, we apply the k-medoids algorithm to shrink down one year to four representative days. We call the novel approach Dynamic System Evaluation (DSE) test. In this work, we compare the annual efficiency factors of three energy conversion systems: a micro combined heat and power system (mCHP), a ground-source heat pump (GSHP) and an air-source heat pump (ASHP). For this purpose, we use three different types of building performance simulation software as well as three different test facilities. The systems were investigated on two test benches each and result in annual efficiencies with relative deviations of Δηrel,mCHP,HiL=0.6%, ΔSCOPrel,GSHP,HiL=0.9% and ΔSCOPrel,ASHP,HiL=11.3%.

Improving the Energy Performance Certificate recommendations accuracy for residential building through simple measurements of key inputs

The Energy Performance Certificate (EPC) allows building users to be informed and aware of the quality of the buildings in terms of energy needs. Additionally, the EPC includes a future for existing buildings, which is the incorporation of a Recommendation list of Measures (RLMs) to improve their energy performance in a cost-effective way. This has risen the question if this tool can provide trustful cost-effective recommendations due despite the use of standardized inputs. This study focuses on estimating the impact of using measured ventilation rate, heating set point and airtightness on the profitability of the recommendations. The study is based on a common dwelling in Norway, comparing results obtained with a Building Performance Simulation Software, following the Norwegian standard for energy certification and with the use of measured ventilation rate, airtightness and real heating set points. The results show that the performance gap can be reduced significantly just by adopting these inputs, increasing the confidence on the RLMs and reducing the uncertainty of the investment.

Improving the Energy Performance Certificate recommendations’ accuracy for residential building through simple measurements of key inputs

The Energy Performance Certificate (EPC) allows building users to be informed and aware of the quality of the buildings in terms of energy needs. Additionally, the EPC includes a future for existing buildings, which is the incorporation of a Recommendation list of Measures (RLMs) to improve their energy performance in a cost-effective way. Which have risen the question if this tool can provide trustful Cost-effective recommendations due despite the uses of standardized inputs. This study focuses on estimating the impact of using measure ventilation rate, heating set point and airtightness on the profitability of the recommendations. The study is based on common dwelling in Norway, comparing results obtained with a Building Performance Simulation Software, following the Norwegian standard for energy certification and with the uses of measured ventilation rate, airtightness and real heating set points. The results show that the performance gap can be reduced significantly just by adopting these inputs, increasing the confidence on the RLMs and reducing the uncertainty of the investment.