An introduction to the Numerical Simulation Laboratory at the University of Texas

The Numerical Simulation Laboratory (NSL) was started in 1971 in order to address a fundamental problem facing both practicing design professionals and architecture students. That is, that although architects are aware that their design decisions influence the energy demand of buildings; there was, and still is, little information available which can be used to help determine the precise quantitative significance that each architectural decision has on energy demand.The original purpose of the NSL was to address this problem within the academic context. Since then most of the analytical capabilities developed have also been used as research as well as design aids.     

Changing family systems in Ghana and its effects on access to urban rental housing: a study of the Offinso Municipality

Individualization of the family system in Ghana has implications for residential housing access particularly in urban areas. In this paper, the authors examined the effects of the changing family system on access, demand and supply of rental housing. The cross-sectional study design was adopted with Offinso Municipality as a case study. Through a multi-stage sampling approach, structured and unstructured questionnaires were used to collect data from 100 renters and 100 landlords. Findings revealed a reduction in the supply of rental housing while increasing demand as a result of the changing family system. Rental housing prices were also found to have increased by 86.17% between the years 2010 and 2015. Findings from the study based on preferences of new family systems for privacy and comfort are also likely to address the problem of scarcity of rental housing and associated escalating rental housing prices .     

Improving energy performance of school buildings while ensuring indoor air quality ventilation

Energy conscious design of school buildings, as well as deemed-to-satisfy provisions in a Performance Based Energy Code, should address the problem known as the energy efficiency—thermal comfort—indoor air quality dilemma (EE-TC-IAQ Dilemma). In warm and moderate climates, the large internal heat sources usually found in school buildings prevent achieving thermal comfort without active cooling in summer, but are not sufficient to eliminate the need for heating in winter. Commonly used air-conditioners do not improve air quality, while natural ventilation induces uncontrolled energy losses. In this study, a step by step process was used for the development of deemed-to-satisfy design solutions, which cope with the EE-TC-IAQ Dilemma, for a performance based code. A distinction is made between improving building design variables and improving ventilation schemes. Results indicate that implementation of improved ventilation schemes in an otherwise well designed energy-conscious building result in savings of 28–30% and 17–18% for northern and southern classroom orientations, respectively.     

Ancient vernacular architecture: characteristics categorization and energy performance evaluation

Building has significant impacts on the environment and natural resources. The emerging world energy and environment challenges demand a substantial revolution of building design philosophies, strategies, technologies, and construction methods. Vernacular architectures, built by people whose design decisions are influenced by traditions in their culture, have been gleaned through a long period of trial and error and the ingenuity of local builders who possess specific knowledge about their place on the planet, and thus are valuable in promoting climate-specific passive building technologies to modern buildings. This study introduced an approach to categorizing distinct vernacular regions and evaluating energy performance of ancient vernacular homes as well as identifying optimal constructions using vernacular building techniques. The research conducted an extensive computer energy modeling for a number of representative ancient vernacular architectural characteristics observed for different climatic regions. The vernacular test subjects were compared against those established according to the International Energy Conservation Code and those generated by the optimization software. The simulation results of the energy models suggest that considering traditions seen in ancient vernacular architecture as an approach to improving building energy performance is a worthwhile endeavor and a scientific guidance can help enhance the performance. The study indicates that, although many vernacular dwells exist in the world, it is challenging (but desired) to package vernacular architecture traditions and quantitative design knowledge to modern building designers. This project is the first part of a much larger project that intends to create a knowledge base of vernacular building traditions that will include information about not only the energy performance of traditional building techniques, but also address areas of cost, material availability and cultural traditions.     

Towards global benchmarking for sustainable homes: an international comparison of the energy performance of housing

Over the past 15 years, house building standards across the western world have begun to address ecologically sustainable development (ESD) principles. Amongst the range of environmental sustainability issues arising from housing construction and occupation, the energy demand for heating and/or cooling to maintain thermal comfort has the longest history and is most widespread in policy and regulation. Since energy in our homes is mainly fossil-derived, a key issue is global climate change impacts. Since greenhouse gas emissions can be emitted in various locations across the globe with similar results, it follows that a given greenhouse gas emission arising from residential space heating and cooling has approximately equal impact, irrespective of the location of the building. These emissions are therefore an appropriate candidate for benchmarking internationally, yet there have been few attempts to undertake this activity. This paper reports on a study undertaken in Australia which compares the thermal energy performance of housing in the United States, Canada, UK and Australia. The comparison is based on energy ratings of over 50 house designs from the comparison countries. Each design was assessed as being current and verified as complying with rather than significantly exceeding local regulatory requirements. Issues in design of both the buildings and the modelling tool used are highlighted, and the results are presented. Conclusions are drawn on the reasons for wide variations in thermal energy performance, the implications for benchmarking, and the case for globally consistent housing environmental performance policies and regulation.     

浅析住宅建筑设计中的节能设计

随着我国国民经济的发展，人们的生产生活对能源的需求量日益提高，能源紧缺问题已经成为了一个全球性的问题，亟待解决。为了响应节能环保的号召，住宅建筑设计开始向节能方向发展，本文对其进行了深入的分析。     

Spatial comparison of renewable energy supply and energy demand for low-carbon settlements

Cities are responsible for a large part of primary energy demand and emissions worldwide. Hence, the use of renewable energy sources (RES) is becoming a key issue in the international debate on the sustainability of urban development models. Most of the literature addresses this issue by focusing on metropolitan areas, disregarding analyses that can support urban design at smaller scales. This paper presents and applies a method to estimate and compare the potential supply of RES and the energy demand of buildings (EDB) at local scale by: (a) performing a spatial estimation of the potential exploitation of RES; (b) performing a spatial estimation of EDB, by considering their characteristics and location, as well as the urban morphology and the settlement design; (c) assessing the spatial congruence between supply and demand patterns. Four RES were analyzed: solar irradiation, ground-source heat, wood biomass and hydropower from existing drinking water supply systems. Suitability maps for each energy source were first developed, and then combined to obtain a composite map, which was eventually compared with the EDB map. The method is based on spatial and statistical analyses conducted in a geographical information system (GIS), using data layers coming from a range of different sources. The case application is represented by an alpine municipality in Trentino, northern Italy. Even though the proposed approach is affected by uncertainties and data scarcity, it showed how datasets and tools available today can be used to provide spatial estimates of RES suitability for exploitation, supporting the selection of areas that are intrinsically suitable for the design of low-carbon settlements.     

工业建筑抗震关键技术研究#br#

对工业建筑抗震的关键技术难题,建立动态多目标抗震设防理论,创建承载力、刚度、延性相互匹配的量化性能指标体系;提出体系层次化、构件梯次化的抗震设计方法,并给出相应的量化控制准则,解决了工业建筑防地震连续倒塌的技术难题;基于结构耗能能力和耗能需求的逻辑关系提出抗震冗余度需求比的概念,并给出量化分级评价标准;提出基于等能量原理的抗震优化设计方法,理顺钢结构抗震设计中的刚度、强度和延性的逻辑匹配关系,弥补现行规范的若干不足;提出设备-结构耦联效应简化设计方法,并给出考虑耦联作用的界限指标;依据现有的地震危险性研究成果,建立地震地面运动峰值加速度的重现期调整系数确定方法,攻克特定后续使用年限条件下抗震性能评价的关键技术难题;研发质量可调TMD减震系统、特种功能材料、在役预应力加固工艺等系列技术,有效解决连续生产条件下的抗震性能提升问题。     

夏热冬冷地区住宅窗设计研究

夏热冬冷地区住宅在开窗上普遍忽视“夏热冬冷“的气候特点,作者对这些问题及产生的原因进行了归纳,并结合自己在夏热冬冷地区所作的大量实验和实践,对该地区住宅窗户设计进行了量化的分析.最后,针对夏热冬冷地区的气候特点,本文提出能够兼顾“夏热“和“冬冷“两种极端要求的住宅窗户的节能设计技术策略.     

浅谈太阳能建筑设计

高效利用太阳能提供给建筑的复合能量,以满足建筑的使用功能需求,实现安全、便利、舒适、健康的环境,是太阳能建筑设计的目标。研究开发利用可再生能源,为建筑供能,是解决建筑能耗问题的一个有效途径。主要阐述了太阳能供热采暖、太阳能热泵等太阳能与建筑一体化技术,以及存在的问题,并展望其发展前景。     

Overcoming problems in house energy ratings in temperate climates: A proposed new rating framework

This paper first demonstrates that an efficient design for a house in conditioned operation mode differs from that for the same house in the free-running operation mode, and that this is a primary reason for the inability of current energy based rating schemes to adequately assess the performance of passive design in a temperate climate. We examine the Australian Nationwide House Energy Rating Scheme as an example of this problem. A new practical framework for a house rating scheme is then presented. In this proposed framework, the efficiency of a house design is evaluated with reference to its thermal performance in free-running mode, in addition to its projected energy loads in conditioned operation mode. The study uses simulation to evaluate the thermal performances of houses, and employs multiregression analysis to develop the framework. The reliability of proposed framework as compared to the current energy based rating scheme is demonstrated. By attributing more value to the performance of houses in the free-running than the conditioned operation, it is assumed that policy objectives for reducing energy demand for space heating and cooling in the residential building sector are more likely to be achieved.     

营造可持续建筑蓄能围护结构的新思路及新方法

随着能源供求失衡日益加剧,建筑蓄能节能的重要性不断凸显。营造具有高效蓄能及可调节能力的可持续蓄能围护结构,对于建筑节能具有重要意义。本文从居住者的热舒适需求出发,通过反问题思路,提出了被动式及主动式建筑中可持续室内环境营造的一些新思路和新方法。研究发现,被动式建筑围护结构理想热质体热性能具有相变材料的特征,即热容随温度的分布接近δ函数形式。并进一步开展了建筑用相变材料的研发及应用研究,研制了建筑用定形相变材料和微胶囊化相变材料,克服了传统相变材料易泄露和导热系数偏低等缺点。最后,提出了主被动式建筑围护结构和相变材料一体化的系统应用方案,并通过实验及模拟验证了其节能舒适效果,为相变材料和建筑蓄能围护结构一体化的设计及应用提供指导。     

Analysis of an information monitoring and diagnostic system to improve building operations

This paper discusses a demonstration of a technology to address the problem that buildings do not perform as well as anticipated during design. We partnered with an innovative building operator to evaluate a prototype information monitoring and diagnostic system (IMDS). The IMDS consists of a set of high-quality sensors, data acquisition software and hardware, and data visualization software including a web-based remote access system, that can be used to identify control problems and equipment faults. The information system allowed the operators to make more effective use of the building control system and freeing up time to take care of other tenant needs. They report observing significant improvements in building comfort, potentially improving tenant health and productivity. The reduction in the labor costs to operate the building is about US$ 20,000 per year, which alone could pay for the information system in about 5 years. A control system retrofit based on findings from the information system is expected to reduce energy use by 20% over the next year, worth over US$ 30,000 per year in energy cost savings. The operators are recommending that similar technology be adopted in other buildings.     

Energy use in the life cycle of conventional and low-energy buildings: A review article

A literature survey on buildings’ life cycle energy use was performed, resulting in a total of 60 cases from nine countries. The cases included both residential and non-residential units. Despite climate and other background differences, the study revealed a linear relation between operating and total energy valid through all the cases. Case studies on buildings built according to different design criteria, and at parity of all other conditions, showed that design of low-energy buildings induces both a net benefit in total life cycle energy demand and an increase in the embodied energy. A solar house proved to be more energy efficient than an equivalent house built with commitment to use “green” materials. Also, the same solar house decreased life cycle energy demand by a factor of two with respect to an equivalent conventional version, when operating energy was expressed as end-use energy and the lifetime assumed to be 50 years. A passive house proved to be more energy efficient than an equivalent self-sufficient solar house. Also, the same passive house decreased life cycle energy demand by a factor of three – expected to rise to four in a new version – with respect to an equivalent conventional version, when operating energy was expressed as primary energy and the lifetime assumed to be 80 years.     

Energy storage using weights hydraulically lifted above ground

Renewable energy sources constitute an ever-growing share of the total electrical market; but, the intermittency and instability issues make it difficult to dispatch these sources directly into the grid. Energy storage represents a promising solution to overcome this obstacle. Among energy storage solutions, pumped hydro energy storage is largely considered the most technologically and financially feasible, though having some drawbacks. In this paper, a new design is introduced to address the major challenges associated with the conventional pumped hydro energy storage. The proposed storage solution does not require tall water tank towers or long piping; rendering it more cost effective and implementable. It is also scalable to operate over a wide range of capacities depending on the electrical surpluses. Beyond this, the design provides a constant pressure and faster discharge, furnishing a quick response to instantaneous demand fluctuations.     

Construction cost and energy performance of single family houses: From integrated design to automated optimization

The single family home market is facing increasing challenges in managing environmental issues. The required objective of building energy performance can be achieved by limiting extra cost, integrating building design, and using the most appropriate and readily available materials. However, standard computations, such as the French building energy code used here, require vocational expertise that involves managing separate processes and numerous design variables. The design is therefore restricted to well-known techniques, especially for small constructions. In this paper, the usual stakeholder constraints and possible developments in design practice are considered through the use of real product databases and vocational tools to calculate construction costs. In the first stage, which takes into account cost and energy demand, an integrated approach to building envelope design is detailed, including a semantic system to automate the process. Then an optimization method (a genetic algorithm) is proposed to assess energy performance and the cost of the building envelope. This process is illustrated as a case study for a single family house. The results highlight various optimal solution domains specific to the case study, which can be further managed through a decision support system.     

Experimental and numerical analysis of heat transfer and airflow on an interactive building facade

The envelope of a building is mainly responsible for its energy demand. Different kinds of double skin facades (DSFs) are nowadays used as a building envelope to reduce the energy demand and improve aesthetical view of buildings. Although DSF are already extensively used, their thermal performance is not well understood. This study presents a decoupling method capable to evaluate thermal performances and analyze fluid phenomena in a DSF. The solar radiation effects were evaluated with an analytical model and computational fluid dynamics (CFD) simulations were used to evaluate complex flow and thermal effect on a commercial DSF. With the decoupling approach to account for the effects of solar radiation and flow, the numerical results obtained by the CFD approach agree well with the experimental data collected on a full scale test room with a ventilated DSF. The method can be used to establish a database to develop a tool for DSF design.     

关于暖通空调设计方案评估体系的若干思考

暖通空调系统方案设计是整个暖通空调系统生命周期中最为关键的一环。本文分析了暖通空调设计方案评价中需要注意和考虑的几个问题，在指出暖通空调设计方案评价特殊性的基础上，突出了评价过程的目的动态性，强调应以人为本，以用户的需求（满意度）为终极的目的进行评估决策。最后讨论了暖通空调设计方案评估的内容，包括安全性、经济性、耗能、室内环境品质（IEQ）、可靠性、灵活度、环境影响、灵活性和可维护性等。建议从整体上进行综合评价。为我国暖通空调设计方案评估体系的进一步深入研究提供参考。     

Parametric study and multi objective optimization of window frame geometry

This paper describes a parametric study on window frame geometry with the goal of designing frames with very good thermal properties. Four different parametric frame models are introduced, described by a number of variables, such as dimensions of particular parts of the frame and thermal conductivity of the materials. In the first part of the study, a process of sensitivity analysis is conducted to determine which of the parameters describing the frame have the highest impact on its thermal performance. Afterwards, an optimization process is conducted on each frame. An attempt is made to optimize the design with regard to three objectives: minimizing the heat flow through the frame, maximizing the net energy gain factor and minimizing the material use. Since the objectives contradict each other, it was found that it is not possible to find a single solution that satisfies all of them. Instead, a range of semi-optimal solutions can be identified, from which the designer can select, according to their needs. A genetic algorithm was successfully used to address this problem. In the final part of the study, detailed simulations of energy use in a building are conducted to validate the results based on simplified, static simulations.     

Applying a multi-objective optimization approach for Design of low-emission cost-effective dwellings

Modern buildings and their HVAC systems are required to be not only energy-efficient but also produce fewer economical and environmental impacts while adhering to an ever-increasing demand for better environment. Research shows that building regulations which depend mainly on building envelope requirements do not guarantee the best environmental and economical solutions. In the current study, a modified multi-objective optimization approach based on Genetic Algorithm is proposed and combined with IDA ICE (building performance simulation program). The combination is used to minimize the carbon dioxide equivalent (CO₂-eq) emissions and the investment cost for a two-storey house and its HVAC system. Heating/cooling energy source, heat recovery type, and six building envelope parameters are considered as design variables. The modified optimization approach performed efficiently with the three studied cases, which address different summer overheating levels, and a set of optimal combinations (Pareto front) was achieved for each case. It is concluded that: (1) compared with initial design, 32% less CO₂-eq emissions and 26% lower investment cost solution could be achieved, (2) the type of heating energy source has a marked influence on the optimal solutions, (3) the influence of the external wall, roof, and floor insulation thickness as well as the window U-value on the energy consumption and thermal comfort level can be reduced into an overall building U-value, (4) to avoid much of summer overheating, dwellings which have insufficient natural ventilation measures could require less insulation than the standard (inconsistent with energy saving requirements) and/or additional cost for shading option.