The future of high-performance buildings

Welcome to this edition of Architectural Science Review. In this edition, a number of issues, which are concerned with the question of what might comprise the nature of high-performance building in the future. High-performance building is a recent development. This crystal ball might lead to a new direction for research and practice. This idea seems to embrace a range of issues concerning the use of technology to improve the performance of buildings. However, there appears to be a lack of clarity about what comprises a high-performance building; there are competing definitions as to what comprises a high-performance building, how does it differ from sustainable building or indeed a ‘green building’ (Alulayet et al. 2015). The Energy Policy Act of 2005 defined high-performance building ‘as one that integrates and optimizes all major high performance building attributes, including energy efficiency, durability, life-cycle performance and occupant productivity’ (High Performance Building Council 2016). Best practice high-performance buildings (HPBs) are found in many case studies; however, what are the attributes of HPBs that are important? The papers in this edition show some important attributes of HPBs and also some of the emerging metrics that can be used to measure the performance of these attributes.

The first paper by Amirhosein Ghaffarianhoseini, Umberto Berardi, Husam AlWaer, Seongju Chang, Edward Halawa, Ali Ghaffarianhoseinifand Derek Clements-Croome explores the question of ‘What is an intelligent building? Analysis of recent interpretations from an international perspective,’ provides an examination of the nature an Intelligent Building (IB) for the future. The first part of the paper provides a review of existing definitions.

Back to 1988, an IB was defined as ‘one which has an information communication network through which two or more of its services systems are automatically controlled, guided by predictions based upon a knowledge of the building and usage, maintained in an integrated data base’. (Leifer 1988)

More recently the IB has become more focused on issues of sustainability, so the constituents of sustainable IBs are ‘the “smart values” concerned with digital (cyber), Intel and sentient technologies that assist with the integration of human, collective and artificial intelligence.’

Hence the authors argue … ‘In recent years, the notion of intelligent buildings (IBs) has become increasingly popular due to their potentials for deploying design initiatives and emerging technologies towards maximized occupants’ comfort and well-being with sustainable design.’

The paper has a review of the directions of IB from different regions of the world and synthesis these into four key performance areas; the authors concluded

The IB offers a new building design paradigm through embedded intelligence leading towards attainment of optimized functions of a building in real time. As a result, the rate of adoption of building automation, embedded intelligence, and advanced sophisticated systems is increasing in some parts of the world, resulting in increasing numbers of buildings labeled intelligent, smart, and green although as has been indicated these terms are sometimes mixed up and their distinctions blurred.

Discussions about the future of IBs focuse on a number of Key Performance Indicators (KPIs). These are (KPI-1) Smartness and Technology Awareness, (KPI-2) Economic and Cost Efficiency, (KPI-3) Personal and Social Sensitivity and (KPI-4) Environmental Responsiveness. These factors are clearly drivers or barriers in the move towards more IBs. They are buildings that can accommodate the more readily future needs at a range of scales from the individual to the city scale. So one might conclude that many of the KPIs also can be applied to HPBs.

The next paper looks at one of these KPIs: Economic and Cost Efficiency. By Marc Ó'Riain and Jim Harrison, it is called ‘Cost-optimal passive versus active nearly Zero Energy Buildings (nZEB). How cost-optimal calculations for retrofit may change nZEB best practice in Ireland.’ This paper examines the important issues of how to improve the performance of the existing building stock to improve building performance. The building of the future is likely to be one that has been retrofitted or likely to be, the question is how to retrofit our existing building stock into HPBs. The importance of the research comes from the state of the building stock and the continual building obsolescence. Research into sustainable retrofitting has been carried out and the roadmaps for achieving higher performance are drawn. The principle used here is that when elements of the building deteriorate and need replacing then it is common to use the existing technology used in the building. However, a principle of sustainable retrofitting is to replace the existing technology with better performing systems (Hyde et al. 2012). This approach is taken in the case study examined here. This principle is often complicated with differing elements of the building needing retrofitting at one time hence a decision-making system is needed. Often this requires a comparison between the passive systems and the active systems. The main research question concerns identifying what are the cost optimum strategies for retrofitting buildings in cool climates such as the U values and or new heating, ventilation and air conditioning systems since in a market situation it is likely that these will be built. The authors report that there is a bias towards lower capital-intensive cost strategies and service-based strategies; ‘In all cases the cost-optimal package has no fabric improvements … improving fabric can lower primary energy demand, but it is expensive.’ The other report ‘finds that fabric retrofit is cost-optimal even in the context of much lower U Values.’ However … ‘The paper concludes that the proposed Irish cost-optimal nZEB retrofit packages may drive design strategies towards active solutions, and away from fabric-driven retrofits.’

The next paper falls under the KPI of Environmental Responsiveness. The paper by Yuan Shi, Chao Ren, Yingsheng Zheng and Edward Ng is called ‘Mapping the urban microclimatic spatial distribution in a sub-tropical high-density urban environment.’ This paper examines the effects of urban densification and associate anthropogenic heat gain on the microclimate of area of the subtropical housing in Hong Kong. By modelling the microclimate through bioclimatic mapping of area of the city, it is possible to determine the Physiological Equivalent Temperature of these areas and potential discomfort to occupants. The move to HPBs potentially addresses these issues; using less energy they would not only contribute less to the sources of pollution that drives but also generate less waste heat thus reducing the overheating effects on the microclimate.

The next two papers are concerned with school buildings. They use differing methodologies to address the same KPI. The first is located in Chile. The paper entitled ‘A parametric analysis of simple passive strategies for improving thermal performance of school classrooms in Chile,’ is by Maureen Trebilcock, Beatriz Piderit, Jaime Soto and Rodrigo Figueroa. The study examines the thermal performances of three climates in Chile: cool, Mediterranean and arid. Most schools except those in cold conditions do not have heating or cooling with an absence of energy conservation regulations for schools. This study aims to provide survey of the thermal conditions inside primary school classrooms. The first part of the study involved monitoring of the schools in winter and summer. In cold climates, heating was only required where internal temperature reached 12°C, which the research argues is low. The second part of the study examined methods to improve the buildings using passive systems. A parametric analysis is provided using a standard classroom as the base case building to optimize the building thermal performance for the various climates. The conclusion from the study showed the need for airtightness and insulation in the cold climate with solar control and ventilation in the hot arid climate. The Mediterranean climate required attributes of both; however, the cool climate strategies can work against the hot climate strategies and can lead to inconsistent results. The future research by the authors will be on solar control.

The next paper is called ‘Energy consumption optimization in schools sector in Jordan,’ by Omaimah Ali Al-Arja and Tala Samir Awadallah. The study is located in a hot arid climate. The first part of the paper examines the need for the research. Importantly, the authors cite the existing energy benchmarks for schools in Jordan as between 2 and 6 kW/m²/year. The objectives of the research are first to carry out a study of the energy consumption of existing school buildings, and second to focus on the façade as an element to miminize heating and cooling loads and finally to develop a database for future design. A typical base case classroom is used to carry out a parametric study. The authors make recommendations to establish a regulatory base for minimum design criteria requirements for school buildings’ main facades, in order to reduce energy demand and provide indoor thermal comfort, for hot arid climates. An interesting consequence of this paper is that the collection of energy consumption data for the school sector is underway which can lead to better understanding the energy intensity of the school sector in Jordon. This practice is used in Australia as a measure of the level of performance of buildings in particular states or areas. In this way, the impact of policy decisions and local codes can be evaluated.

Another paper on school buildings covers the broader perspective of sustainability. The paper by Jorge S. Carlos reports on the ‘Sustainability assessment of government school buildings in Portugal.’ It examines three indicators for sustainability: materials, energy and daylighting. The building typology of these buildings uses strategies such as small windows facing north and large windows facing the equator, in order to minimize losses on the north side while gaining solar heat on the south. The author argues … ‘Solar gains and daylight are key passive strategies to improve energy performance without incurring additional construction and operational costs.’ The research examines the effectiveness of the building performance in these areas. A case study methodology using a Building Simulation and Daylight Factor analysis is used. A typical vernacular classroom located in Covilhã with cold winter and hot summer climate was used as the base case building. This is similar to many of the 7000 such classrooms in Portugal.

The performance of the demonstrated case building shows that solar gains reduced the heating load in winter; however, the internal daylight level in the building was insufficient. The case study shows the issues of thermal performance in mixed climates where there is both the need for heating and cooling. The use of trees as shading devises is found in this example for reducing the heat gains. Deciduous trees are preferred in the approach since they lose their leaves in winter permitting solar gain while excluding heating in summer. This type of mixed climate is difficult to optimize the passive design parameters, since strategies for the heating season are often not useful in the cooling season.

The next paper also examines issues of sustainability. An important issue is to develop effective indicators for measuring sustainability. The paper by Sallam and Mohammad Refaat M. Abdelaal is titled ‘Relative weight of water efficiency credits: as an indicator to enhance buildings’ environmental assessment tools performance.’ Many of the environmental assessment tools use a ‘Principles to Indicator’ model to determine the sustainability of a project. Sustainable Design Principles are determined and the performance indicators are created from an index. Scores for each indicator are added and a total score is provided (Hyde et al. 2007). However, a crucial issue with these indexes is weightings given to the indicators. The author argues that a local climate-based weighting approach is needed. For example, energy is often seen as the most important indicator due to its links with carbon pollution. Regions such as the Middle East have an arid and semi-arid environment; hence, the authors argue that this is equal to if not more important than energy and that the sustainability index for these types of regions should address this logic. The paper provides a review of the indicators and weightings for six tools for addressing water efficiency in residential buildings.

‘Energy consumption’ used as a factor of efficiency is an important dimension in the final paper by Xiancun Hu and Chunlu Liu. Called ‘Energy productivity and total-factor productivity in the Australian construction industry,’ the authors examined the productivity of the Australian construction industry in terms of its energy consumption. The methodology involves the use of a Malmquist index method. This methodology uses an input to output model to indicate the level of productivity in a given system. The index takes into account attributes of the construction industry and different types of efficiency, such as cost, pure technical and allocated efficiency changes. Output factors come from data on energy consumption of this sector. Results suggest that ‘Energy productivity and total-factor productivity of the whole industry improved by 2.8% and 0.7%, respectively, in the two decades, which primarily resulted from technological advancement.’ The authors point out that this approach is needed since energy is rarely examined in the context of efficiency in an economic and environmental context and hence provides a new methodology to inform the green building debate.

There are a number of challenges that come from the papers presented which are equally applicable to HPBs. HPBs are equated high-tech systems. In the first paper for example, the authors report … 

Moreover, the study demonstrates a lack of empirical evidence that IBs actually deliver the benefits claimed for them. IBs of today, being significantly affected by the ‘tech push and market pull’ scenario, are highly unaffordable due to the high cost of available intelligent systems and the lack of widespread expertise for monitoring their operations, specifically in the context of small-scale commercial, educational and residential buildings.

A further challenge to the design process for HPBs is the metrics used to measure performance. A common way to do this is to use the sustainability index, which establishes sustainable design principles from which criteria can be established. Each criterion is assigned indicators and the method of rating criteria is devised to add together evaluation for each indicator. Called a Principle to Indicator method this approach is now commonly used in many Green Building Rating schemes. In the paper by Sallam et al, this approach discusses the need for making changes to the sustainability index and the direction for improvement.

A new book by Yudleson discusses these measures and argues that while voluntary certification systems are available, they need modification to make them more effective (Yudelson 2016). The paper by Carlos shows the way passive design is a cost-effective step to sustainable building design and to HPBs. Sallam argues that a way to improve these systems is to give a more regional weighting to the index to be more effective. Marc Ó'Riain et al. suggest that one further challenge is the operational performance of buildings and developing expertise to carry this out. The future of HPBs will be shaped by the technologies that are available and affordable. Retrofitting existing buildings to make them high performance is a challenge. The roles of passive design of these buildings in particular the façade and the relations to the immediate microclimate are important opportunities in this regard.