Low Energy Building Design Research Articles

Impact of occupant behavior on optimal multi-objective solutions for the design of low-energy buildings

The occupant behavior plays a fundamental role in the actual performance of the buildings, especially for very low energy buildings. Since inconsistencies are discovered post-occupancy, known as Energy Performance Gap, it is necessary to better represent the occupants when optimizing the design of buildings. In this context, a multi-objective optimization of a low energy building was carried out for three different French climates with two models of occupant behaviors. The first is a standard fixed scenario (SF) while the second is an agent-based tool (NoMASS) that predicts occupancy scenarios according to sociodemographic characteristics and estimates occupants’ interactions with windows, external shadings and lighting based on probabilistic models. The results obtained show that the occupant model significantly influences the expected performance of the building as NoMASS model estimates greater heating needs and improved summer comfort. However, for our case study, there is no influence of the accuracy of representation of occupant behavior on the optimal solutions of building design. The optimization could be carried out with a less detailed model, thus reducing calculation times while maintaining comparable optimal results. The performance of the optimal solutions obtained can then be refined by simulating with the most detailed model.

Mechanisms of climatically responsive building and principles of low-energy building design

Mechanisms of climatically responsive building and principles of low-energy building design

Feasibility Analysis of Nearly Zero-Energy Building Design Oriented to the Optimization of Thermal Performance Parameters

The effective control and reduction of building energy consumption are major global focuses. The building sector is responsible for over 40% of all direct and indirect CO2 emissions. Nearly zero-energy buildings have been the subject of aims and regulations from several developed nations. An office building located in the severe cold region of China was chosen for this case study. The building was equipped with multiple NZEB technologies. Building indoor environment parameters and energy efficiency indexes were used as performance targets, and a performance-based design approach was used to optimize building design parameters. Thermal performance of the building envelope, airtightness, energy demand, and indoor thermal environment were tested according to different evaluation criteria. The total energy demand was as low as 53.93 KWh/(m2·a), and this can be attributed to the exceptional insulation of the building. In this test, the indoor thermal environment comfort was satisfactory. This study can be used as a reference for the design and evaluation of low-carbon buildings and low-energy buildings.

The Transition to Integrated Renewable Energy: A Framework for Low Energy Building Design

Following the Paris Agreement in 2015, global attention to global warming countermeasures has intensified, as climate change is a major threat to human societies, fundamentally linked to energy consumption and greenhouse gas emissions. Given the huge impact of buildings on energy consumption, changes must take place towards a sustainable energy transition by using renewable energies such as solar energy in order to push buildings to near zero energy consumption. In this context, our work consists of clarifying the nearly zero energy building (NZEB) concept and of reviewing research articles focusing on the use of renewable energy sources (RES) in an efficient way, based on solar energy.

Model predictive control of a thermal chimney and dynamic solar shades for an all-glass facades building

Controlling the operation of HVAC (Heating, Ventilation, and Air-Conditioning) systems is arguably the most effective way to reach desired indoor conditions in buildings. Nevertheless, such control may involve complex dynamics when dealing with passive energy technologies. In this paper, we focus on maximizing the passive operation of HVAC in a novel low-energy building design by means of Model Predictive Control (MPC). The low-energy building design, located in The Green Village, consists of a thermal chimney and solar shades over all-glass facades to provide the required indoor air conditioning as passively as possible. The MPC controller is based on a transient grey box model and a hierarchical control architecture to satisfy thermal comfort while minimizing the active energy requirements. Using sensor data collected from the actual building in April and May 2021, the grey box model shows a good agreement with the measurements, since the variance accounted for is 90% in most cases. Moreover, via a comparative study among different MPC architectures we show that managing the distinct transient response of each component (shades and chimney) is the best for successful overall performance – e.g. considering linear agents for shading and nonlinear agents for ventilation. The hierarchical MPC architecture established outperforms the standard ones by 22.7% in terms of control performance. We also compare the proposed MPC approach against the rule-based control method currently implemented in the actual building, which indicates that MPC demands about 78% less active energy, highlighting the proposed optimization-based control approach.

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.

Design of low-energy buildings in densely populated urban areas based on IoT

As part of city planning and urban studies, it is customary to use the phrase urban density to describe people and other human activity and development throughout a certain area of land. Urban regions in affluent nations are not only more densely populated (DPUA), but they also have a greater population density per unit of land area than rural areas do as well. In densely populated urban areas, public transportation is more plentiful, reducing travel times making them more efficient. Greater affluent residents in metropolitan areas can also benefit from modern high-rise structures, which offer more breathing room. An energy-efficient design and features provide great living standards and comfort while using little energy and releasing minimal carbon dioxide in this sort of housing. In the absence of or rare usage of conventional active and passive heating and cooling systems, Smart sensors and other IoT devices make up the Internet of Things (IoT). IoT presents cities with new potential for using data from sensors in their infrastructure to improve traffic flow and reduce pollution. The more crowded and congested a city is, the more dissatisfied its residents are. There are numerous negatives to urban life, including high living costs, congestion, pollution, crime, and traffic, yet the benefits exceed the risks. Clean up the air by reducing the amount of energy used and using alternate modes of transportation. Provide services like garbage disposal and housing through private–public partnerships. Urban planning should include planting trees and the maintenance of municipal green areas. There are many advantages to living in densely populated places, such as better healthcare, better amenities, and faster emergency response times. The innovative DPUA-IoT approach proposed in this study is only one example of these advantages. Rapid population expansion is harmful to achieving economic and social progress and sustainably managing the natural resource base. However, there is still a large disparity between the interests of the commercial and public sectors when it comes to reducing fertility.

A Sustainable Approach to Build Insulated External Timber Frame Walls for Passive Houses Using Natural and Waste Materials

This paper presents structures of timber-framed walls designed for passive houses, using natural and waste resources as insulation materials, such as wool, wood fibers, ground paper, reeds (Phragmites communis), and Acrylonitrile Butadiene Styrene (ABS) wastes. The insulation systems of stud walls composed of wool–ABS composite boards and five types of fillers (wool, ABS, wood fibers, ground paper, and reeds) were investigated to reach U-value requirements for passive houses. The wall structures were designed at a thickness of 175 mm, including gypsum board for internal wall lining and oriented strand board (OSB) for the exterior one. The testing protocol of thermal insulation properties of wall structures simulated conditions for indoor and outdoor temperatures during the winter and summer seasons using HFM-Lambda laboratory equipment. In situ measurements of U-values were determined for the experimental wall structures during winter time, when the temperature differences between outside and inside exceeded 10 °C. The results recorded for the U-values between 0.20 W/m2K and 0.35 W/m2K indicate that the proposed structures are energy-efficient walls for passive houses placed in the temperate-continental areas. The vapour flow rate calculation does not indicate the presence of condensation in the 175 mm thick wall structures, which proves that the selected thermal insulation materials are not prone to degradation due to condensation. The research is aligned to the international trend in civil engineering, oriented to the design and construction of low-energy buildings on the one hand and the use of environmentally friendly or recycled materials on the other.

Feasibility assessment of adopting distributed solar photovoltaics and phase change materials in multifamily residential buildings

• Feasibility study to assess adopting PVs and BioPCMs in multifamily residential designs. • Energy-efficient VRF-HVAC systems are considered in multifamily residential designs. • Simulation-based assessment is conducted with LCCA of multifamily residential designs. • Effects of annual site energy use intensity and availability are investigated and discussed. • 35–50% Of annual energy needs can be satisfied, with lifecycle cost reductions of 6–9%. Given the growing environmental concerns due to climate change, the combination of renewable energy systems and feasible design optimization strategies of buildings, has been considered as a promising integrated solution to promote sustainable residential infrastructure and maintain carbon emission reductions. As part of promoting sustainable residential infrastructure development projects involving low-energy buildings, this study evaluates the feasibility of applying distributed solar photovoltaic (PV) systems and Bio-phase change materials (BioPCMs) with energy-efficient variable refrigerant flow (VRF) systems in multifamily residential buildings. To this end, this study conducts lifecycle cost analysis (LCCA) of low-energy multifamily residential building (LEMRB) design with energy-efficient VRF type systems, distributed solar energy generation systems (PVs), and BioPCMs. To enable LEMRB design, Korean medium-sized multifamily residential buildings on the national level, are selected as a case study. The results demonstrate that the application of both solar PV systems and BioPCMs to medium-sized multifamily residential buildings significantly help to reduce 35.03–49.78% of the total annual energy needs of each medium-sized multifamily residential building in various Korean climatic locations. Accordingly, the lifecycle cost (LCC) of low-energy medium-sized multifamily residential buildings showed significantly feasible in all Korean climate locations, as the discounted payback (DPB) period of investment costs is ranged from 5 to 8 years. However, further systematic studies to optimize the efficiency of solar energy systems and phase change materials are required. These include investigating more residential design alternatives and considering the effects of uncertainty and degradation on LEMRB lifecycle performance for achieving more sustainably and cost-effectively low-energy multifamily residential buildings in the future.

A Tool for Optimal Refurbishment Design of Low-Energy Buildings

We propose a model that aims to fulfill the following three necessities: the demand for refurbishing the existing built environment, the lack of a reliable means to help architects navigate among the numerous possible solutions for low-energy constructions, and the need for a multi-function tool to analyze buildings as complex systems. We introduce the Optimal Refurbishment Design (ORD) model that is a novel tool to help architects with the refurbishment of an existing building or the design of a new one. The ORD shows four innovative aspects. First, it opens the way to passive building design while focusing on affordable solutions. Second, its core component is based on mathematical optimization. Third, it simultaneously outputs optimal thermal mass and insulation of all the required elements in the building. Fourth, it automatically accounts for the user’s needs and local regulations. Unlike most of the approaches in the Literature, the ORD’s outputs are not limited by any pre-defined set of materials or strategies. We tested the ORD using a realistic study case of refurbishment, and found that the renovated house achieved the energy consumption of a Passive House by lowering its annual heating/cooling consumption by 23% with a payback period of less than 5 years.

The impact of daylight presence on cooling strategies: energy simulations of a test room in Austin, Texas, and Geneva, Switzerland

In order to understand how to reduce energy consumption in buildings, all factors affecting occupant comfort and behavior must be considered. Previous work from EPFL has elucidated the influence of daylight on thermal perception and its resulting potential to reduce cooling loads in a controlled test space in Geneva, Switzerland with three different illumination levels (130 lux, 600 lux, and 1400 lux) and under three different indoor air temperature levels (19°C, 23°C, 27°C). Occupants perceived the temperature as up to 2°C cooler when exposed to daylight, leading to reduced cooling loads. For climates with high cooling loads for much of the year, such as Austin, Texas, this reduction could yield significant benefits for low-energy building design. Simulations show the total amount of energy saved from adopting this strategy in Austin, Texas.

Dwelling infiltration and heating energy demand in multifamily high-rise and low-energy buildings in Korea

Building energy demand is an important factor in reducing energy consumption and greenhouse gas emissions in the building sector. Current low-energy building design concepts have decreased energy demand mainly by improving the thermal performance. The Korean government has continuously reinforced thermal performance by region and wall. Multifamily high-rise buildings (MFHRBs), a representative residential building type in Korea, have a powerful air-driving force caused by wind and stack interactions in winter. The weather-driven airflow produces (1) outdoor air infiltration across the envelope and (2) interzonal airflow from household entrance doors adjacent to unconditioned corridors. The two factors should be considered depending on weather conditions and airtightness for main airflow paths (such as envelope and household entrance doors) in the total heating energy demand. Nevertheless, airtightness is still not proposed according to regional weather conditions and airflow paths, as has been done for the exterior thermal performance. This study provides information about how and how much airtightness should be determined for MFHRBs to achieve low-energy buildings or to meet existing or new building energy demand standards. The leakage areas for the household envelope and entrance door are suggested by region in Korea for the different satisfaction levels of the passive-house energy demand standard (15 kWh/m2·year). The suggested leakage areas show the uncertainty of the dwelling airtightness metric (such as ACH50) adopted internationally for the energy demand standard. Moreover, the existing limit (0.6 ACH50) is suitable for southern regions but required to be lower elsewhere, especially in the central regions of Korea.

Building Information Modeling-Based Building Energy Modeling: Investigation of Interoperability and Simulation Results

There is increasing need to apply building information modeling (BIM) to low energy buildings, this includes building energy modeling (BEM). If a building energy model can be flawlessly generated from a BIM model, the energy simulation process can be better integrated within the design, can be more competent, and timesaving. However, concerns about both the reliability and integrity of the data transfer process and the interoperability between the BIM and BEM prevent any implementation of BIM-based energy modeling on a large scale. This study addresses the accuracy and integrity of BIM-based energy modeling by investigating how well Autodesk's Revit (BIM), in conjunction with two of the most used energy modeling programs (BEM) known as DesignBuilder and Virtual Environment (IES-ve), were integrated in terms of interoperability, including location and weather files, geometry, construction and materials, thermal zones, occupancy operating schedules, and HVAC systems. All misrepresented data during the interoperability process were identified, followed by benchmarking between the BIM-based energy modeling simulation outcomes and the actual energy consumption of the case study, to assess the reliability of the process. The investigation has revealed a number of interoperability issues regarding the BIM data input and BEM data interpretation. Overall, BIM-based energy modeling proved to be a promising tool for sustainable and low energy building design, however, the BIM to BEM process is a non-standardized method of producing building energy models as it varies from one modeler to another, and the BIM to BEM process. All these might slow down any possible application for the process and might cause some uncertainties for the professionals in the field applying it.

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.

Optimization and cost analysis of thickness of vacuum insulation panel for structural insulating panel buildings in cold climates

Structural insulation panels (SIPs) are considered promising building products that achieve the low-energy goal, and its potential energy performance can be further improved by combining it with a vacuum insulation panel (VIP) in cold climates. The aim of this study is to determine the optimal SIP with VIP (VIP–SIP) thickness and to minimize the energy cost. We conduct a VIP-SIP thickness optimization and cost analysis for five cold sub-regions using P1-P2 methods. First, we develop an energy model using the building energy simulation software OpenStudio considering the VIP aging effect, and the accuracy of this model is validated using field test data. Results indicate that as climates become colder from Cold area B to Severe Cold area A, the optimal VIP thickness increases from 3.5 mm to 31 mm, whereas the optimal PU thickness decreases from 66.875 mm to 174.2 mm. In addition, the total cost saving rate increases from 40.5% to 47.9%, and the discounted payback period decreases from 12.59 years to 8.98 years, indicating improved economic feasibility. Furthermore, the influence of the P1 value and VIP price on the optimal thickness and total cost are also discussed. The findings of this study confirm the economic feasibility of combining SIP with VIP in cold areas, and provide feasible parameters for the design of low-energy buildings in cold areas of China.

On the development of exponential regression analysis concerning occupant density and space form to predict energy consumption of outpatient department in hospital

In outpatient area of medical buildings, the distribution of people and energy consumption are significantly different when the space form scale changes. To obtain the simulation results of energy consumption under different occupant densities and different space forms, then establish a predictive regression model which can quantify the influence on building energy when space form scale and occupant density change, the Design Builder software is used to simulate the energy consumption. On the basis of the above simulations, this paper explores the characteristics and rules of energy-saving form of outpatient area which could provide references for the low-energy medical building design. The results show that when the total area of the outpatient department is constant, the energy consumption decreases when the occupant density increases; when the width of the peripheral zone increases, the energy consumption increases accordingly. The specific value of energy consumption can be predicted by regression model.

A renewable energy scenario for a new low carbon settlement in northern Italy: Biomass district heating coupled with heat pump and solar photovoltaic system

In the framework of the building sector de-carbonization, the case of a new nearly zero-energy district, located in the Milan urban area (Italy), is presented. In particular, the scope of the work is to demonstrate that the proposed energy concept, based on the combination of low-energy building design and high-efficiency technical systems, allows the reduction of the final energy uses. After the evaluation of the energy needs, a low-temperature and small-size wood biomass district thermal plant was designed to be integrated with groundwater heat pumps (GWHP) and solar photovoltaic (PV) systems, taking up the challenge to design an almost full-renewable urban district by means of a Multi-Energy System. The core is a biomass boiler coupled with a small combined heat and power (CHP) unit with a twin-screw steam expander (TSSE). The heat produced by the CHP satisfies a consistent fraction of space heating and domestic hot water (DHW) needs during the winter season. GWHPs coupled with PV satisfy remaining thermal needs in winter and the entire thermal needs in mid-season and in the summer period. The obtained outcomes prove the benefits of the combination of a wood biomass CHP with GWHPs and PV with a significant share of renewable energies. • Provide an overview of the evolution of district heating networks. • Propose a solution for energy decarbonization of new settlements. • Show how biomass CHP, PV systems and heat pumps may be successfully integrated. • Propose an effective control strategy to enhance local-RES self-consumption.

Study on thermal and energy-saving performances of pipe-embedded wall utilizing low-grade energy

Building energy performance improvement has received much attention in recent years. In this paper, the pipe-embedded wall integrated with low-grade energy was reported, which can be used to reducing the energy consumption effectively on space heating and cooling. The computational fluid dynamics (CFD) method was adopted to study the thermal performance of the pipe-embedded wall. An indoor experiment was conducted to verify the accuracy of the numerical model. The simulation data was agreed very well with the experimental result. The influence of inlet water temperature, mass flow rate and location of the embedded pipe has been evaluated under steady state. The results show that the pipe-embedded wall could achieve the best cooling or heating performance, when the pipes are in the middle location of the wall. The mass flow rate has little effect on the heat loss of the wall, but has a significant effect on the heat transfer of the circulating fluid. In the transient analysis, the pipe-embedded wall can reduce 13% of total heat gain in cooling season and 33% of heat loss in winter. The results indicate that the pipe-embedded wall has the advantages to utilize directly low-grade energy for reducing building cooling/heating load. The study also provides guidance for the design and optimization of low-energy buildings.

The effect of the daylight zone on lighting energy savings

Daylighting is the cornerstone of low energy building design. Therefore, the adoption of a daylight – harvesting lighting control system can substantially increase lighting energy savings. These are strongly depended on the determination of daylight zones (DZ) which in turn help to identify the lighting loads that must be controlled separately. The Daylight Zone (DZ) is defined in ANSI/ASHRAE/IES Standard 90.1-2016 as the floor area substantially illuminated by daylight. However, the DZ is defined differently in several standards and building codes. Lighting design plays also an important role since it determines the number of luminaires in the daylight zone and thus the resulted energy savings due to the daylight harvesting techniques. Each one of these luminaires inside the DZ should be dimmable and must be controlled by either a stand-alone photosensor or one photosensor per control zone. In order to investigate the influence of the DZ in lighting energy savings several simulations were conducted in five (5) office spaces - part of the reference office building used to determine cost optimal energy performance for office buildings in Greece. DZ area was estimated using three (3) different definitions according to a) EN 15193.1 as implemented in Greek regulation of Energy Efficiency in Buildings, b) CEN Technical Committee 169/WG11 ‘Daylight’, and finally c) using dynamic daylight metrics for typical working hours in all four cardinal orientations. Results indicate that due to the differentiation of the DZ depth as this is calculated by the aforementioned methods, there is an associated variation of the calculated lighting energy savings. The extend of the DZ varies between 30-100% of the total area in each office when DZ is calculated using the geometrical method, 50-100% when daylight factors are used and 30-60% with dynamic daylight metrics. The number of luminaires within the DZ vary between 30-100% in the same space depending on the calculation method, the geometry of the room and the Window to Floor Area. As already mentioned, lighting energy savings for the examined test spaces vary, since these are strongly depended on method for the calculation of the DZ’s depth from 61% to 89%, 53-72% and 69-91% correspondingly.

Space Design for Thermal Comfort and Energy Efficiency in Summer : Passive cooling strategies for hot humid climates, inspired by Chinese vernacular architecture

Passive cooling for thermal comfort in summer is a big issue in low-energy building design. An important reason is global warming because global warming increases the number of cooling degree days. In addition, the energy demand of buildings has increased rapidly due to both the improvement of living standards and the globalisation of modern architecture. And finally, cooling a building is especially a challenge in countries where few resources are available. Passive cooling techniques, where solar and heating control systems are applied, largely depend on the design of the urban morphology and the building shape. The first research question is therefore: What is the relationship between spatial configuration, thermal environment and thermal summer comfort of occupants and how to apply spatial configuration as the passive cooling strategy in architectural design? Space is the empty part of a building, but its volume is important for the activities of occupants. Architects define the general spatial structure of a building mainly in the early design stages. There they define the spatial properties of a building, i.e. how the spaces are connected and what are the boundary conditions between the spaces. The final research question of this research therefore is: What is the relationship between spatial configuration, thermal environment and thermal summer comfort and how to apply spatial configuration as passive cooling strategy in architectural design in the early stages? In order to answer this research question, this dissertation is divided into two main parts.