A GP-Based Hierarchical Objectives Decision-Making Method for Building Energy Efficiency Optimization

Building energy efficiency, which is critical in reducing environmental impact, has become one of the most important objectives of building designs. In order to precisely express the goals of building designs, and help decision makers estimate the ultimate performance of design schemes in advance when searching for the optimal building design, the Goal Programming Model (GPM) is introduced in this study to provide a solution for explicit design objective delivery and multi-stakeholder involved decision-making support. In this proposed method, EnergyPlusTM works as a simulation engine to search for the relationship between design parameter combinations and building energy consumption. Simultaneously, Genetic Algorithm (GA) is used to improve the efficiency of overall building energy performance optimization by processing multiple iterations. A case study with five possible design scenarios was dedicated in this study to implement the proposed optimization method, and the optimization results verified the capacity of the established GP-based optimization method to satisfy various design requirements for decision makers and/or stakeholders, especially in facing the hierarchical objectives with different priorities. In this case, the envelope-related variables, including the exterior wall and window, serve as optimization objectives. The optimization is carried out under the ideal air conditioning system, considering different energy usage patterns. Meanwhile, comparing with the vague and restricted expression of objectives in multi-objective optimization, the proposed GP-based optimization method provides explicit trade-off relationships among various objectives for designers, which improves the practical value of the optimized designs, so as to ensure the project success and facilitate the development of green buildings.

Heat Flux and Thermal Characteristics of Electrically Heated Windows: A Case Study

Energy loss through windows can be high relatively compared to other opaque surfaces because insulation performance of fenestration parts is lower in the building envelope. Electrically heated window systems are used to improve the indoor environment, prevent condensation, and increase building energy efficiency. The purpose of this study is to analyze the thermal behaviors of a heated window under a field experiment condition. Experiments were conducted during the winter season (i.e., January and February) with the energy-efficient house that residents occupy. To collect measured data from the experimental house, temperature and heat flux meter sensors were used for the analysis of heat flow patterns. Such measured data were used to calculate heat gain ratios and compare temperature and dew point distribution profiles of heated windows with input power values under the changed condition in the operating temperature of the heated glazing. Results from this study indicated that the input average heat gain ratio was analyzed to be 75.2% in the south-facing and 83.8% in the north-facing at nighttime. Additionally, compared to January, reducing the operating temperature of the heated glazing by 3 °C decreased the input energy in February by 44% and 41% for the south-facing and north-facing windows, respectively. Through such field measurement study, various interesting results that could not be found in controlled laboratory chamber conditions were captured, indicating that the necessity of establishing various control strategies should be considered for the development and commercialization of heated windows.

Framework for Evaluating Financial Impacts of Technical Risks Related to Energy-Efficient Renovation of Commercial Office Buildings

Energy efficiency in the building sector is a priority of the EU Commission to achieve carbon neutrality by 2050. Renovation of the existing buildings, which are currently responsible for approximately 40% of EU energy consumption and 36% of the greenhouse gas emissions can lead to significant energy savings. This paper presents the EEnvest calculation method for evaluating the financial impacts of technical risks related to energy-efficient renovation of commercial office buildings. The evaluation method aims to increase investors’ confidence and boost investments in the renovation of the existing building. Through a series of Key Performance Indicators (KPI), the technical and financial risks impact is evaluated. The results are strictly connected to building features, climatic conditions, solution sets and mitigation measures specific to the building energy efficiency project.

External Thermal Insulation Composite Systems (ETICS) from Industry and Academia Perspective

External Thermal Insulation Composite System (ETICS) is a commonly used solution in EU countries to increase building energy efficiency. The article describes ETICS in terms of environmental impact from two perspectives, i.e., industry and academia. In EU countries, ETICS manufacturers to place construction products to the market must subject it to the assessment and verification of constancy of performance (AVCP). The basis of this process is the European Technical Assessment (ETA). Based on the number of issued and valid ETAs for ETICS and the number of Environmental Product Declarations (EPDs), the dimension of sustainability issues was discussed. Analysis of one of the environmental indicators (Global Warming Potential—GWP) for ETICS with EPS, XPS, and MW showed only a general trend. However, there are significant differences between the values of the GWP and other environmental indicators that one can use for future AVCP of construction products. In the light of the research described in the paper, it seems reasonable to conclude that AVCP for ETICS in terms of sustainability will be challenging to implement in practice-based only on environmental indicators according to EN 15804. The article also reviews scientific publications on the sustainability of ETICS.

Assessment of Zero Energy Prefabricated Accessory Dwelling Units in Support of New Zealand Housing Needs

<p>Problem statement: The demographics of New Zealand are changing and the country is getting older. The literature shows the housing needs of older people are different, and that many would prefer to stay in their existing neighbourhood and age in place. In addition to the shortage of houses, low residential densities, the fast growth of land and house costs over income, and an aging population are all current issues in New Zealand housing. Projections also show the shortage of energy resources and environmental pollution will affect the future of housing, as the housing industry is responsible for over one-third of global energy use and CO₂ emissions. Aim of the research: This thesis aims to design and evaluate the practicality and efficiency of a prefabricated Accessory Dwelling Units (ADU) as a partial response to New Zealand housing needs. Prefabrication was selected as the method of construction as it has been claimed to be more efficient in terms of energy and material use, as well as leading to a shorter construction time and lower environmental impacts. The use of ADUs could increase residential density and add to the housing stock by using existing developed land and infrastructure. ADUs also offer smaller houses within the existing social context, which the literature suggests is the main housing requirement of older people. As a result, the ADU in this research was designed to suit older residents, whilst recognising that it would also be suitable for small households of all ages. Methodology: This research used design as a tool with which to explore the potential of prefabricated ADUs as a contribution to New Zealand housing needs. The design was then tested against housing needs by using Life Cycle Analysis (LCA). This part of the research was conducted in the three phases of life-cycle energy, life-cycle cost, and life cycle CO₂ emissions of the ADU as designed. Results: While the transport limitations pushed the design to be narrow (the maximum allowed load width was 2.55m), the Lifemark accessibility standard asked for doors, corridors, and spaces wide enough to ease the movement of disabled people. Despite these difficulties, it was possible to design an ADU which could be manufactured in New Zealand and transported anywhere in the country without any need for over-dimension load permissions. However, the analysis in the last phase, looking at the ADU during its life span, showed there was no substantial difference between its performance and that traditionally made houses. The results of the analysis suggest that, despite the importance of the construction method, the building energy efficiency, CO₂ emissions and cost, the environmental impact of a house is more dependent on the choice of materials than the method of making it. Future research: The results suggest the importance of further investigation into the choice of materials used to make residential buildings and the effect such choices have on life-cycle impact. There is also a need to seek feedback on the ADU as designed from both potential users and potential manufacturers.</p>

Assessment of Zero Energy Prefabricated Accessory Dwelling Units in Support of New Zealand Housing Needs

<p>Problem statement: The demographics of New Zealand are changing and the country is getting older. The literature shows the housing needs of older people are different, and that many would prefer to stay in their existing neighbourhood and age in place. In addition to the shortage of houses, low residential densities, the fast growth of land and house costs over income, and an aging population are all current issues in New Zealand housing. Projections also show the shortage of energy resources and environmental pollution will affect the future of housing, as the housing industry is responsible for over one-third of global energy use and CO₂ emissions. Aim of the research: This thesis aims to design and evaluate the practicality and efficiency of a prefabricated Accessory Dwelling Units (ADU) as a partial response to New Zealand housing needs. Prefabrication was selected as the method of construction as it has been claimed to be more efficient in terms of energy and material use, as well as leading to a shorter construction time and lower environmental impacts. The use of ADUs could increase residential density and add to the housing stock by using existing developed land and infrastructure. ADUs also offer smaller houses within the existing social context, which the literature suggests is the main housing requirement of older people. As a result, the ADU in this research was designed to suit older residents, whilst recognising that it would also be suitable for small households of all ages. Methodology: This research used design as a tool with which to explore the potential of prefabricated ADUs as a contribution to New Zealand housing needs. The design was then tested against housing needs by using Life Cycle Analysis (LCA). This part of the research was conducted in the three phases of life-cycle energy, life-cycle cost, and life cycle CO₂ emissions of the ADU as designed. Results: While the transport limitations pushed the design to be narrow (the maximum allowed load width was 2.55m), the Lifemark accessibility standard asked for doors, corridors, and spaces wide enough to ease the movement of disabled people. Despite these difficulties, it was possible to design an ADU which could be manufactured in New Zealand and transported anywhere in the country without any need for over-dimension load permissions. However, the analysis in the last phase, looking at the ADU during its life span, showed there was no substantial difference between its performance and that traditionally made houses. The results of the analysis suggest that, despite the importance of the construction method, the building energy efficiency, CO₂ emissions and cost, the environmental impact of a house is more dependent on the choice of materials than the method of making it. Future research: The results suggest the importance of further investigation into the choice of materials used to make residential buildings and the effect such choices have on life-cycle impact. There is also a need to seek feedback on the ADU as designed from both potential users and potential manufacturers.</p>

Research Progress of Photo-/Electro-Driven Thermochromic Smart Windows

Thermochromic smart windows can automatically control solar radiation according to the ambient temperature. Compared with photochromic and electrochromic smart windows, they have a stronger applicability and lower energy consumption, and have a wide range of application prospects in the field of building energy efficiency. At present, aiming at the challenge of the high transition temperature of thermochromic smart windows, a large amount of innovative research has been carried out via the principle that thermochromic materials can be driven to change their optical performance by photothermal or electrothermal effects at room temperature. Based on this, the research progress of photo- and electro-driven thermochromic smart windows is summarized from VO2-based composites, hydrogels and liquid crystals, and it is pointed out that there are two main development trends of photo-/electro-driven thermochromic smart windows. One is exploring the diversified combination methods of photothermal materials and thermochromic materials, and the other is developing low-cost large-area heating electrodes.

Development of an Integrated Performance Design Platform for Residential Buildings Based on Climate Adaptability

Building energy waste has become one of the major challenges confronting the world today, so specifications and targets for building energy efficiency have been put forward in countries around the world in recent years. The schematic design stage matters a lot for building energy efficiency, while most architects nowadays are less likely to make energy efficiency design decisions in this stage due to the lack of necessary means and methods for analysis. An integrated multi-objective multivariate framework for optimization analysis is proposed for the schematic design stage in the paper. Here, the design parameters of the building morphology and the design parameters of the building envelope are integrated for analysis, and an integrated performance prediction model is established for low-rise and medium-rise residential buildings. Then, a comparison of the performance indicators of low-rise and medium-rise residential buildings under five typical urban climatic conditions is carried out, and the change patterns of the lighting environment, thermal environment, building energy demand, and life cycle cost of residential buildings in each city under different morphological parameters and design parameters of the building envelope are summarized. Specific analysis methods and practical tools are provided in the study for architectural design to ensure thermal comfort, lighting comfort, low energy consumption, and low life-cycle cost requirement, and this design method can inspire and guide the climate adaptation analysis and design process of low-rise and medium-rise residential buildings in China, improve architects’ perception of energy-saving design principles of low-rise and medium-rise residential buildings on the ontological level, as well as provide them with a method to follow and a case to follow in the actual design process.

Plan for the Sustainability of Public Buildings through the Energy Efficiency Certification System: Case Study of Public Sports Facilities, Korea

This study examines strategies for energy efficiency in public buildings in Korea and the implementation of certification systems. It also identifies the actual plan status and discusses improvements at the institutional level. The target is the national sports centers, where the discussion on energy efficiency has been assiduous, as they have recently expanded regionally in Korea. Among the 541 national sports centers in Korea, 90 facilities for which a preliminary review was performed on the plan by the National Public Building Center were analyzed. The energy efficiency plan is realized through Building Energy Efficiency, Zero Energy Building, and Green Standard for Energy and Environmental Design certifications. As a result of analyzing the plan status, omissions or errors in certification were confirmed in about 10% of each, even though more than 80% of the facilities were subject to mandatory application. In Korea’s condition, to revitalize the practice of the system, it is necessary to expand the government’s publicity and support initiatives, use differential application of evaluation items, and strengthen incentives. This study provides meaningful results and suggestions for implementing an energy efficiency system at the national level under similar conditions in the future.