Reference Building Models Research Articles

Building stock energy modeling to assess annual progress in stock energy efficiency and carbon emission reduction of commercial buildings

Short-term progress assessments of carbon dioxide emission reductions are essential for nations to meet their medium/long-term targets. Bottom-up building stock energy modeling (BSEM) methods can contribute to this issue but have not been applied because of the need to represent short-term building stock dynamics in building systems and energy conservation measures (ECMs). To fill this gap, this study developed a BSEM framework that integrates top-down building stock decomposition, including building systems and ECMs, and bottom-up physics-based energy demand quantification using reference building models representing building stock segments. The framework was verified through a case study of a Japanese commercial building stock. The results indicate that the developed model effectively captures the short-term dynamics and contributions of the technologies. Although there are significant errors in estimating some building subsectors and end uses, the model predicts the changes in the aggregated energy consumption with acceptable accuracy. The Japanese 2030 emission reduction target cannot be achieved with the current technology deployment trends; however, the shortfall can be addressed by applying additional measures. Owing to its applicability to diverse building stocks, the framework promotes the use of BSEM for policy assessment and evidence-based policymaking for climate change mitigation.

Analysis of the necessity of revising the building energy efficiency certificate for non-residential buildings in South Korea

The Building Energy Efficiency Certification (BEEC) program is a crucial government policy aimed at reducing building energy consumption and greenhouse gas emissions in numerous countries, including South Korea. This study aims to evaluate the achievable BEEC level by designing a typical building with a construction permit and analyze the appropriateness of the awarded BEEC level. We collected 327 samples of non-residential buildings from South Korea's architectural administration system and established reference building models from these samples. The buildings were categorized into four use types (office, educational, retail, or cultural) and large or small sizes. We evaluated the energy consumption of the reference buildings and assigned them a BEEC level. Retail buildings exhibited the highest energy consumption, followed by office, cultural, and educational buildings. All reference buildings had an energy consumption of less than 260 kWh/m2/yr and were awarded a BEEC level of 1 to 1++, indicating energy efficient buildings. Non-residential buildings, reflecting common design trends, achieved a BEEC level of at least level 1 without additional efforts to enhance energy efficiency. We recommend the South Korean government should revise the current BEEC rating criteria and review the certification evaluation methodology. The results of this study strongly advocate for continuous improvement of the BEEC certification system. This study is expected to enhance the effectiveness of energy efficiency policies for buildings and advance related policies.

Operational Strategy of a DC Inverter Heat Pump System Considering PV Power Fluctuation and Demand-Side Load Characteristics

With the increase in application of solar PV systems, it is of great significance to develop and investigate direct current (DC)-powered equipment in buildings with flexible operational strategies. A promising piece of building equipment integrated in PV-powered buildings, DC inverter heat pump systems often operate with strategies either focused on the power supply side or on the building demand side. In this regard, the aim of this study was to investigate the operational strategy of a DC inverter heat pump system for application in an office building with a PV power system. Firstly, the PV power fluctuation and demand-side load characteristics were analyzed. Then, a series of heat transfer and heat pump system models were developed. A reference building model was developed for simulating the performance of the system. A control logic of the DC inverter heat pump was proposed with a certain level of flexibility and capability considering both the characteristics of the PV power generation and the demand-side heating load. MATLAB/Simulink 2021 software was used for simulation. The simulation results show that the DC inverter heat pump is able to regulate its own power according to the change signal of the bus voltage such that the DC distribution network can achieve power balance and thus provide enough energy for a room. This study can provide a reference for developing flexible operational strategies for DC inverter heat pump systems. The proposed strategy can also help to improve the systems’ performance when they are applied in buildings with distributed PV systems.

Alternative window wall ratio of glasses with different solar heat gain coefficient and solar transmittance and their effect on total energy consumption in alternative directions

Energy simulation model of the building of Eskişehir Technical University Industrial Engineering Department Academic and Administrative Staff rooms were created in this study carried in the scope of energy efficiency and performance of buildings. In the aforementioned energy simulation mode, in line with the International Measurement, Verification and Energy Needs Standards and Protocol (IPMVP) “energy consumption verification”; heating energy, indoor-outdoor environment and climate data were defined, energy consumption verification was carried out and a realistic model was achieved. Using the realistic model achieved, alternative directions were applied to alternative window wall ratios thereby calculating “reference energy consumptions” in “reference building models”. Energy consumptions, calculated by applying alternative glass types to reference models, were then compared with reference energy consumptions

The Effect of Different Heavy Overhang on Structural Performance in Reinforced Concrete Structures

There are many structural factors that affect the earthquake performance of buildings. Heavy overhang is the one of these factors which made to increase the storey area on the storeys above the ground storey. Within the scope of this study, the effect of different heavy overhangs on the earthquake performance of the building was investigated, which are commonly used in reinforced-concrete (RC) structures. A sample RC building with no heavy overhangs was chosen as the reference building model for numerical analysis. The numerical analyses were carried out for a total of 16 structural models designed by adding heavy overhangs of different lengths and to different facades of the reference building model. The obtained results were compared with the results of the reference structure model without heavy overhang to reveal the heavy overhang effect. The period, base shear force, displacement and performance levels were obtained for each structural model. It has been determined that the base shear force, period and total mass increase with the increase of heavy overhangs, while the earthquake performance decreases. The obtained results clearly revealed that the earthquake performance was negatively affected with the increase in the amount of closed heavy overhang.

Performance-Based Assessment of RC Building with Short Columns Due to the Different Design Principles

Many factors affect the earthquake vulnerability of reinforced concrete (RC) structures, constituting a large part of the existing building stock. Short column in RC structures is one of the reasons for earthquake damage. Significant damages may occur due to brittle fractures in structural elements when the shear resistances are exceeded under the effect of high shear stress in short columns formed due to architectural and topographic reasons. This study created structural models for three situations: the hill slope effect, band-type window and mezzanine floor, which may cause short column formation. The structural analyses by SAP2000 were compared with the reference building model with no short columns. Structural analyses were performed separately according to strength-based and deformation-based design approaches in the updated Türkiye Building Earthquake Code (TBEC-2018). Short column formation; the effects on soft-storey irregularity, the relative storey drifts, column shear force, plastic rotation in columns, roof displacement, base shear force and column damage levels were investigated. As a result of the analysis, it was determined that the relative drifts from the first floor of the building decreased significantly due to the band-type window and slope effect, which caused the second storey to fall into the soft-storey status. In addition, short-column formation caused a significant increase in both plastic rotation demand and shear force in short columns.

Simulation case study of stack pressure impact on thermal load in high-rise buildings

The reference building models in the EnergyPlus tool do not consider the stack effect. This is not an issue for small and low-rise buildings. However, this is significant in evaluating the heating and cooling load of high-rise buildings. This study evaluates and quantifies this stack effect in building energy simulation, EnergyPlus. The high-rise commercial building model in the EnergyPlus reference building set was used as a simulation test bed. The vertical multi-stories shaft zones were added inside the core zone in the existing building model. Then, the airflow network model was set in EnergyPlus so the internal airflow including the vertical and horizontal directions through the shaft zone as well as the core and perimeter zones were configured. The simulation model was calibrated against the actual pressure distribution between the core and perimeter zones in all floors of high-rise buildings from the literature. This model calibration was conducted manually by changing the discharge coefficient of the openings between thermal zones. The heating and cooling load of the proposed model were compared to the existing model which does not consider the vertical airflow through the shaft zones. The quantification with relative load mismatch was analyzed by floors and environment including the temperature difference between indoor and outdoor, and wind speed. Moreover, the impact of the air mixing and infiltration on the heating and cooling load was quantified. The result of this study reveals the significance of the stack effect in calculating the heating and cooling load.

Development and Test of a New Fast Estimate Tool for Cooling and Heating Load Prediction of District Energy Systems at Planning Stage

During the design and planning stage of a district energy system, the prediction of the cooling and heating loads is an important step. The accurate estimate of the load pattern can provide a basis for the configuration and optimization of the system. To meet the demand in practical application, this paper proposes a fast load prediction method for district energy systems based on a presimulated forward modelling database and KNN (K-nearest neighbor) algorithm and develops it into a practical tool. Owing to the absence of some design parameters at the planning stage, scenario analysis is also used to determine some input conditions for load prediction. In this paper, the scenarios cover three types of building: office, shopping mall and hotel. To test the performance of this new method, we randomly selected 15 virtual buildings (5 buildings for each type) with different design parameters and took their detailed BPS (building performance simulation) model as a benchmark to assess the prediction results of the new method. The index “ratio of the hours with effective prediction” is defined as the ratio of the hours whose relative error of hourly load prediction is less than 15% to the hours whose load is not 0 in the whole year, and the test result shows that this index is not less than 0.9 (90%) for the predicted cooling load of all 45 test cases and the predicted heating load of 25 of the 45 cases. As a research achievement with practical value, this paper accomplishes the programming work of the tool and makes it into a software. The application of this software in the actual project of district energy system is also presented. The performance of the new load prediction tool was compared with the traditional approach commonly used in engineering—the load estimation based on reference building models—and the result shows that the fast load estimate tool can provide the same level of prediction accuracy as traditional simulation methods.

Effects of Lead Core Heating on the Response of Isolated-Base and Fixed-Base Regular and Irregular Reinforced Concrete Structures

In this study, the seismic behavior of isolated- and fixed-base regular and irregular reinforced concrete structures was investigated. For this purpose, a three-dimensional, eight-story reference building model without any irregularity was designed in accordance with the Turkish Building Earthquake Code (TBEC-2018). Later, the building models with irregularities were created using the reference building model. In the building models with seismic isolators and fixed supports, fiber hinges were used for columns and beams to model nonlinear behavior. Moreover, nonlinear behavior at the isolation level was taken into account in building models with seismic isolators. Eleven different earthquake records were scaled using the geometric scaling method. Bi-directional nonlinear response history analysis (NRHA) was performed simultaneously for both horizontal components of the earthquake records in all building models. In addition to boundary analyses (Lower Bound and Upper Bound), which do not take into account the strength loss defined by the codes, analyses considering the strength loss as a result of heating in the lead core due to cyclical motion (Temperature Including) were carried out for building models with seismic isolators. In the analyses, displacement, acceleration, story drift ratio, base shear ratio, and damage mechanisms in the columns and beams obtained from the fixed-base and isolated-base structures were compared. In addition, the results of the analysis, in which the loss of strength due to temperature increase due to cyclical motion in the lead core is taken into account, were compared with the results obtained from the boundary analysis. As a result of the study, it was deduced that significant improvements were observed in the structural behavior of all regular and irregular models with seismic isolators under earthquake effects.

A three-stage decision-making process for cost-effective passive solutions in office buildings in the hot summer and cold winter zone in China

China, with the largest energy consumption system in the world, faces numerous challenges in achieving the government’s commitment to reach a carbon-peak and carbon–neutral target. As the most common public building type in terms of floor area, office buildings have great potential for energy saving and emissions reduction. To meet this target, building designers target passive solutions that can meet the thermal comfort needs of occupants and also reduce energy consumption. This study aims to develop a decision-making method to select optimal solutions from among tens of thousands of design options considering the factors of energy consumption, comfort, and cost. We developed a novel optimization decision approach with the above-mentioned three objectives. The model consists of three stages: 1) the establishment of the reference building model, 2) sensitivity analysis to identify the main influencing variables and 3) the establishment of the optimization and decision-making model by applying NSGA-II and TOPSIS methods. By applying this three-stage decision-making model, this paper first proposes cost-effective passive design solutions for office buildings throughout the Hot Summer and Cold Winter climate zone. Finally, an office building in Shanghai was chosen as a case study to demonstrate the practical implementation of the proposed solutions through a post-occupancy evaluation with a two-year energy auditing and thermal comfort survey. It is evident that the proposed solutions provide support for the new low energy building design guide for office buildings along with necessary revisions to the existing standards for the Hot Summer and Cold Winter climate zone in China.

On the Benefits of Whole-building IAQ, Ventilation, Infiltration, and Energy Analysis Using Co-simulation between CONTAM and EnergyPlus

Publicly available tools to perform whole-building simulation of indoor air quality, ventilation, and energy have been available for several decades. Until recently, these tools were developed in isolation, such as the whole-building contaminant transport and airflow analysis tool, CONTAM, developed by the National Institute of Standards and Technology (NIST) and the whole-building energy analysis tool, EnergyPlus, developed by the U.S. Department of Energy (DOE). The ability to couple these tools during runtime has been implemented through co-simulation, enabling improved analysis of the interdependent effects of temperature and airflow on contaminant transport and energy use on a whole-building scale.This presentation will include the development of a set of coupled reference building models for the purposes of evaluating the potential benefits of using co-simulation between CONTAM and EnergyPlus. A set of Residential Prototype Building Models available from DOE has been modified by NIST and utilized to demonstrate the coupling process and the benefits of this coupling with respect to IAQ and energy analysis, and to evaluate multiple whole-building simulation methods related to infiltration, ventilation, and occupant exposure. These methods include an original EnergyPlus prototype model, the original model with NIST-based infiltration correlations, co-simulation between EnergyPlus and CONTAM, and stand-alone CONTAM simulations. Potential benefits will be explored related to the ability of co-simulation to address the effects of variations in building typology and ventilation system performance on contaminant transport results while leveraging the capabilities of whole-building energy analysis.

Building stock energy modeling considering building system composition and long-term change for climate change mitigation of commercial building stocks

A significant improvement in the building stock energy efficiency is imperative to mitigate climate change. Building stock energy models (BSEMs) that employ reference building models are useful for mitigation analysis. However, most existing BSEMs developed for commercial building stock focus on limited building systems and energy conservation measures, and technology deployments are suggested based on simple vintage-driven scenarios. These approaches are insufficient, particularly for regions where improvements to building insulation performances can have a modest impact. This study aims to establish a BSEM framework to overcome this issue and to validate the framework via its application to the Japanese commercial building stock. The framework develops statistical models for estimating the selection probabilities of system alternatives and utilizes them to disaggregate building stocks. A reference building model is developed for each stock segment. The results show that this approach facilitates the use of multiple technological options considering various factors that affect technological deployments, and it also helps estimate the baseline development of building stocks. Furthermore, the developed model well represents the observed distributions in energy use intensity and estimates the aggregated energy consumption of building stocks with a reasonable accuracy. The baseline development was estimated to reduce the CO2 emission by 18% by 2030 from 2013. Efficiency measures can help avoid the increase in electricity demand caused by electrifying the heat source of heating, ventilating, and air-conditioning and water heating systems. The framework could help extend the scope of BSEM application because BSEM development is not information intensive.

Determination of seismic isolation effects on irregular RC buildings using friction pendulums

This study aims to evaluate influences of isolation made using friction pendulum type isolators on seismic behavior of irregular mid-rise RC frame buildings without shear walls. For this at first, a 4-storey 3D reference building model which have no irregularity is designed as residential building. Afterwards, models including heavy overhang, short column and soft storey irregularities are created through the reference building. A total of 88 nonlinear time history analyses of regular and irregular building models subjected to 11 pairs of ground motion records are performed for non-isolated and isolated cases. There has been a significant reduction in base shear ratios for isolated reference and irregular buildings. Roof drift ratios of isolated-base models are generally higher compared to fixed-base models for both regular and irregular buildings. Unlike the results of roof displacement demands, lower average interstorey drift ratios have been obtained for especially isolated reference and heavy overhang buildings. Evaluations on the effects of the isolation for floor accelerations, interstorey drift ratio (IDR) profiles and damages of structural elements are also given in the paper. This study emphasizes that advances are made in terms of behavior against earthquakes for irregular buildings thanks to isolation.

Energy models for cost-optimal analysis: Development and calibration of residential reference building models for Northern Cyprus

Ambitious energy efficiency goals constitute an important roadmap towards attaining a low-carbon society. Thus, various building-related stakeholders have introduced regulations targeting the energy efficiency of buildings. However, some countries still lack such policies. This paper is an effort to help bridge this gap for Northern Cyprus, a country devoid of building energy regulations that still experiences electrical energy production and distribution challenges, principally by establishing reference residential buildings which can be the cornerstone for prospective building regulations. Statistical analysis of available building stock data was performed to determine existing residential reference buildings. Five residential reference buildings with distinct configurations that constituted over 75% floor area share of the sampled data emerged, with floor areas varying from 191 to 1006 m2. EnergyPlus models were developed and calibrated for five residential reference buildings against yearly measured electricity consumption. Values of Mean Bias Error (MBE) and Cumulative Variation of Root Mean Squared Error CV(RMSE) between the models’ energy consumption and real energy consumption on monthly based analysis varied within the following ranges: (MBE)monthly from –0.12% to 2.01% and CV(RMSE)monthly from 1.35% to 2.96%. Thermal energy required to maintain the models' setpoint temperatures for cooling and heating varied from 6,134 to 11,451 kWh/year.

Evaluation of thermal comfort and air quality of low-income housing in Kampala City, Uganda

This paper presents the results of thermal comfort and air quality studies in naturally ventilated residential buildings in Kampala City, Uganda. Questionnaire surveys were used for obtaining occupant subjective thermal sensation votes. Indoor and outdoor measurements for air temperature (Ta), Mean Radiant Temperature (MRT), relative humidity, air speed, and air quality were done for seven buildings over fifteen days during the month of June 2019. DesignBuilder software was used to develop the reference building model and to simulate strategies for improvement of thermal comfort. Survey results showed that 67.8% of the respondents were comfortable with the indoor thermal environment. The indoor air temperature range was 22.7°C - 27.9°C which lies within the 80% acceptable limits set by ASHRAE 55. The measured indoor MRT range was 24.24°C - 25.57°C. Measured levels of indoor PM2.5 were double the World Health Organization recommended limits, while the levels of PM10 were thrice the recommended limits of ASHRAE 62.1. The CO2 concentrations were within the limits set by ASHRAE 62.1. The developed model predicted comfortable indoor conditions with a temperature range of 23.6°C - 25.3°C based on the 80% acceptable limits set by ASHRAE 55. The results show that majority of occupants preferred cooler temperatures during the day which is justified by the use of adaptive measures to obtain thermal comfort.

The effect of different negative parameters on the performance of steel structures

In this study, we present the effect of various negativity parameters on steel structures that cause post-earthquake damage based on performance-based assessment. In accordance with this purpose, eigenvalue and pushover analysis are carried out for different negativity parameters such as number of story, soft story, short column, hill-slope effect and irregularity in plan for a sample steel structure in this study. Structural models were created over the reference building to cover each negativity parameter within the scope of this study. Natural vibration period, base shear force, target displacements for damage estimation and stiffness values are obtained for each structural model separately. The comparisons with the reference building model results are made. The effect to behaviour of structures is determined and a reduction coefficient is proposed, for each negativity parameter, respectively. The proposed coefficients can be used to determine the risk priority in steel structures. It was concluded that each negativity parameter considered in this study reduces the behaviour of the building under the effect of earthquakes.

Development of reference building models based on statistical data for the analysis of the building heat demand

For the transition of the energy system from the status quo to a point where the political targets are achieved, the largest potentials for energy and CO2 savings are in the building sector, especially due to older unrenovated buildings. For the state of Bavaria, preliminary investigations have shown that approximately 27 % of the total final energy demand is provided for space heating and domestic hot water preparation of the residential building stock. Extensive measures must be taken in this sector for a successful energy transition.To make the best use of available resources, investigations with realistic reference building models are essential. Previous studies have shown that a significant classification of the building stock can performed and large parts of it can be represented with a limited number of reference buildings models. In this study, it is shown that the representativity can be further increased by selective grouping of the categories while keeping the number of necessary models as small as possible. In addition, a method is presented to model reference buildings using statistical data. The methods of grouping and modelling as well as possible applications and outputs of the generated models are shown for a realistic example.

Development of an assessment method for energy performance of residential buildings using G-SEED in South Korea

ABSTRACT A new assessment method for the “Energy Performance” issue in the Green Standard for Energy and Environmental Design (G-SEED) was developed in this study. First, the corresponding issues in green building rating systems in advanced countries were reviewed and analysed, and then a new assessment method that uses dynamic building energy simulation programs was developed. The most important part of the new method was developing guidelines for modelling a reference building using simulation programs. Therefore, details of the simulation inputs for a reference building model were provided, and new guidelines were developed in this study. To evaluate the new assessment method, it was applied to a multi-residential building in Seoul, South Korea, and the results were compared to those from the current assessment method in G-SEED.

Automatic and rapid calibration of urban building energy models by learning from energy performance database

Urban building energy modeling (UBEM) is attracting increasing attention in the energy modeling filed. Unlike modeling a single building using detailed building systems information, UBEM generally uses limited high-level building stock data to infer default assumptions about building characteristics and operations. This practice inherently brings uncertainty to UBEM. This study introduced a novel method of automatic and rapid calibration of UBEM based on the annual electricity and natural gas energy use data by learning the correlations between crucial model input parameters and the building energy use from the reference building models. A case study was presented to calibrate 72 large office buildings built before 1978 in San Francisco. Seventeen model parameters were selected and Monte Carlo sampling was used to create 1000 samples that reasonably represent the parameter space. Then 1000 simulations were performed for the reference building model to create an energy performance database. The results showed that by learning from the energy performance database, it took less than four simulation runs on average to calibrate a building model. After the calibration, the distributions of each parameter were obtained to replace their single predefined default values. For example, the default lighting power density of 21.39 W/m2 was calibrated to be 7.50 W/m2 on average. The case study successfully demonstrated the effectiveness of the novel calibration method for UBEM in the mild climate. The method will be further tested in future for other climate zones and other building types.

Development of new baseline models for U.S. medium office buildings based on commercial buildings energy consumption survey data

Building energy estimation for the building sector under various scenarios are needed for building energy regulation and policy making. This often starts with representative baselines (either empirical baseline or modeled baseline). Commercial Buildings Energy Consumption Survey (CBECS) data is a widely used empirical baseline for U.S. commercial buildings, but none of the existing baseline model are developed to represent the CBECS data. This paper aims to develop new baseline models for the U.S. medium office buildings, which can produce modeled baselines consistent with the CBECS data. First, we introduced the methodology to create baseline models and the criteria to evaluate the performance of baseline models. The methodology consists of three phases: (1) identification of model inputs, (2) model calibration, and (3) model validation with uncertainty analysis. The evaluation index is the coefficient of variation of the root-mean-square deviation (CV(RMSD)) of site energy use intensities (EUIs) between the modeled baseline and empirical baseline. Then 30 new baseline models for two vintages (pre- and post-1980) and 15 climate zones were created. The evaluation shows that the CV(RMSD) is lower than 0.05 for the modeled baselines produced by the new baseline models. As a comparison, the CV(RMSD) is higher than 0.1 for the existing modeled baselines generated by DOE Commercial Reference Building Models. Further analysis shows that the new baseline models are able to capture the uncertainties of the representative features of existing buildings.