Architectural Science Review ISSN: 0003-8628 (Print) 1758-9622 (Online) Journal homepage: https://www.tandfonline.com/loi/tasr20 Energy sufficiency in buildings, a synonym for passive and low energy architecture (PLEA) Hugo Santos, Pouya Samani & Eduardo de Oliveira Fernandes To cite this article: Hugo Santos, Pouya Samani & Eduardo de Oliveira Fernandes (2018) Energy sufficiency in buildings, a synonym for passive and low energy architecture (PLEA), Architectural Science Review, 61:5, 292-297, DOI: 10.1080/00038628.2018.1505332 To link to this article: https://doi.org/10.1080/00038628.2018.1505332 Published online: 10 Aug 2018. Submit your article to this journal Article views: 269 View related articles View Crossmark data Full Terms & Conditions of access and use can be found at https://www.tandfonline.com/action/journalInformation?journalCode=tasr20 ARCHITECTURAL SCIENCE REVIEW 2018, VOL. 61, NO. 5, 292–297 https://doi.org/10.1080/00038628.2018.1505332 Energy sufficiency in buildings, a synonym for passive and low energy architecture (PLEA) Hugo Santos a , Pouya Samani a and Eduardo de Oliveira Fernandes b∗ a Institute of Science and Innovation in Mechanical and Industrial Engineering (INEGI), Porto, Portugal; b University of Porto, Porto, Portugal ABSTRACT ARTICLE HISTORY Energy sufficiency in buildings means making the most of the environmental energy that can be exploited directly by the building’s physics. To happen this requires a full dialogue with place and proper design and materials to respond, as much as possible, to the energy needs within the building, typically related to the provision of comfort and the overall wellbeing of its occupants. It can be said that the Passive and Low Energy Architecture movement, PLEA, has promoted, for over thirty-five years, all avenues for energy sufficiency in buildings through the exploitation of ‘sound architectural’ design potentials. Between the approach of vernacular architecture, particularly relevant in the Mediterranean basin, and the concept of energy sufficiency, there is an opportunity to facilitate, enrichen and clarify the dialogue with energy service stakeholders and related policy makers to result in better architectural design, contributing towards the advancement of PLEA’s perspective, strategy, wisdom and practice. Received 13 July 2018 Accepted 14 July 2018 Introduction In developed countries worldwide, energy demand in buildings frequently represents the majority of all primary energy and, consequently, is responsible for the majority of greenhouse gas (GHG) emissions, representing approximately 40% and 36%, respectively, in the European Union (European Commission 2016). Simultaneously, people typically spend 80% or more (Klepeis et al. 2001) of their lives inside buildings in which thermal comfort and health should be regarded as basic human needs. These make it ever more challenging to meet objectives of improved wellbeing, which traditionally might require further energy for heating, cooling and ventilation, while simultaneously reducing energy demand and GHG emissions. More than ever, it is imperative that decision makers at all levels and scales, as well as designers, architects, engineers and builders, are called upon to play their respective and crucial roles in intelligently answering these challenges in effective ways, within a framework of effective and clearly prioritised strategies and policies (de Oliveira Fernandes 2015). This paper presents the arguments for energy sufficiency as a path towards those goals. A building is an energy system, balancing energy and mass inputs and outputs through it, and one that has not been properly designed and/or built will inevitably fail to meet its occupants’ wellbeing requirements or, conversely, demand more energy to compensate for its shortfalls. The age-old question is still: what constitutes a ‘properly designed building’? In line with the tenets of the Passive Low-Energy Architecture (PLEA) movement, we argue that, first and foremost, the building should act as an extension of its surrounding environment, in full dialogue with the local climate and incorporating the culture and needs of the locality that will over decades, and possibly generations, hrsantos@gmail.com CONTACT Hugo Santos ∗ Present address: Emeritus professor of the University. © 2018 Informa UK Limited, trading as Taylor & Francis Group KEYWORDS Energy sufficiency; designing with the climate; adaptive comfort provide its occupants. This it does by implementing adequate technical solutions that take advantage of natural energy around the site, like the sun and wind (as well as others) and local amenities. While the first buildings were mainly makeshift shelters to keep humans protected, it was quickly learned how to take full advantage of the best of the local climate while protecting against adverse weather, with the limited locally available materials and construction techniques. These aims and constraints gave birth to a multitude of vernacular architectural and technical passive solutions that were naturally adapted to their specific time, place, means and culture. The first industrial revolution, and its subsequent versions, brought the wonder of advanced and active technologies into use, with the energy-dependent machine, so loved for their potential to empower humans in the face of an unruly nature. Architecture was liberated by these developments that gave true freedom in design to create ideal shapes and forms, regardless of their context. Human comfort was no longer a slave of climate. Modern globalized trends in the development and application of building regulations that often dictate acceptable design and architecture forms have long been written to favour buildings that are strongly dependent on heating, cooling and ventilation (HVAC) systems, in effect, purposefully isolating them from their surroundings and completely disregarding local climate potential. While this might be justifiable in extreme climates and other specific contexts such as in some dense urban environments and specific required features, it is concerning to frequently find these sorts of regulatory approaches in places where there is a high potential to run buildings on local natural energy resources, as in temperate regions. Thermal comfort ARCHITECTURAL SCIENCE REVIEW and occupant wellbeing has become increasingly dependent on strict technological solutions resulting in more intensive and often arguably unnecessary, commercial energy use with consequently higher environmental impacts through energyrelated GHG emissions. Continued technological advances and recent climate change threats, including planetary warming and extreme weather events, have only further stimulated the drive to meet thermal energy and indoor air quality needs exclusively through more and more efficient systems and equipment (paradoxically even less resilient than the passive solutions to potential energy systems’ disruption). In turn architects have been decoupled from the challenge of designing to create comfort and wellbeing indoors (Santos, Pereira, and de Oliveira Fernandes 2016). Current terminology trends reflect this same way of thinking. For instance, even within the official regulations and directives at the EU level, all energy-demand reduction options are positioned within a single encompassing classification of ‘energy efficiency’, challenging the path towards sustainability (Shove 2017). In the eyes of policy-makers and many professionals, installing a better heat-pump, more insulation, or solar PV panels on the roof, can all equally contribute to making a building more energy efficient. One could argue, however, that energy efficiency is only strictly applicable, thermodynamically and precisely, to devices and equipment that have defined and measurable ratios of useful energy output to final energy input. Of course, that same rationale can be translated into other kinds of comparisons between some ‘investment’ and an objective ‘outcome’, such as where more thermal insulation can reduce the cost of heating the building, but these are inexact applications of the concept that end up having pernicious impacts in practice. As can be very easily grasped in the above examples, many solutions cannot be adequately defined or quantified using just the logic of energy efficiency. It might be reasoned that it is an acceptable simplification to claim that all ‘energy efficiency’ options ultimately achieve the same goal of reducing commercial energy demand and thus should be compared and analysed simultaneously within the same category. We posit here that this approach leads to a complete disregard of the many qualitative and inherent characteristics of a careful and intelligent passive and low-energy building design. It also disregards the key role of user behaviour in reducing energy use and decouples occupants from their responsibility as the ‘root demander’ of energy in a building and their function as a key player in managing, i.e. reducing, energy use in it. Ultimately, when energy demand in buildings has the potential for such a large impact on the environment, a more rigorous use of language in relation to its management and reduction becomes even more required. This issue of definition is particularly relevant to the PLEA movement. It is fundamentally rooted on the aforementioned principles of vernacular and bioclimatic architectures and passive design, using natural and innovative techniques to drive architectural solutions and urban designs that lie at the heart of global sustainability objectives. Since the early 80’s, PLEA has been a driving force in the evolution of solar design expertise, technologies and strategies for buildings to provide thermal comfort for occupants through sensible design without any additional technical systems, in a ‘design first’ philosophy. 293 The movement often links the putative approaches of today to enhanced versions of the old solutions/approaches from the past that were necessarily attuned to their climate and the place. A design led approach has to be pursued to reduce energy needs in buildings while providing thermal comfort and healthy indoor air for residents (Cole, Brown, and McKay 2010). It is important to note the distinction between ‘energy needs’ and ‘energy demand’. The former refers to the ‘useful energy’ required to achieve a specific purpose, for instance providing heat for warming a given space, while the latter refers to ‘final commercial energy’ required to run a device or equipment, for example electricity to run the electric heater. Energy needs, thus, are established by the physical and operational characteristics of a space or activity regarding a specific objective like providing comfort, renewing indoor air, cooking, lighting, etc., regardless of technology or equipment. On the other hand, energy demand is strictly linked to the technology or device used to provide for a specific need like heaters, ventilators, stove, light bulbs, etc. Current approaches to reducing energy in the buildings sector completely ignore this distinction, be it in policy texts or in professional practice. We propose that acknowledging the concept of energy sufficiency better captures the nuances and advantages of passive building design, while energy efficiency should be restricted to specific fields of application, particularly in the analysis of the technological characteristics of energy systems sensu stricto, be it a piece of equipment or a specific, local, regional or even larger energy systems at the national level. Logically and scientifically, the challenge of reducing energy consumption in buildings must be tackled from its root causes. In this case, the reduction of energy demand in the buildings sector must firstly explore the potential for reducing energy needs (sufficiency) necessary in a building to be fit for purpose for its’ recognised and assumed functions and only then, secondly, ensure energy demand is managed through the energy efficiency of the justifiably needed equipment. Relying exclusively on energy efficient equipment to cope with situations that could have been adequately addressed through the design itself is not only non-intelligent, but also many might say, unethical and, in the face of climate change, absurd. The efforts pursued by PLEA so far, pioneering and opening the path for these approaches, not only require a continuous support in education, practice, industry and the policy arena, but also require recognition of the paramount importance of an energy sufficiency first step in the design process (Alcott 2008). This needs to be considered explicitly as a preemptive action and evaluated separately from the subsequent ‘energy efficiency’ optimisation stages. In 2013 the International Energy Agency (IEA) has explicitly recommended exploring the energy sufficiency performance of a building prior to considering energy efficiency (Figure 1) and renewable energy contributions to low-energy and low-carbon building design (International Energy Agency 2013). Recent regulations in Europe are calling for cost-optimal solution packages, implying that a cost–benefit analysis, based solely on investment cost versus savings on energy over a systems’ lifecycle, can adequately represent the relative merits of the solutions (Thomsen and Wittche 2015). However, experience shows that many of the calculations based on estimated energy savings are often disconnected from the real-world use of buildings 294 H. SANTOS ET AL. Figure 1. The path to follow at the design stage to achieve low-energy and low-carbon building by the IEA (adapted from International Energy Agency 2013). and systems by people (de Wilde 2014). A well-designed building, which relies mostly on passive solutions, is intrinsically more resilient to time and usage patterns than technical systems usually are. The latter are plagued by rebound effects that act to increase effective consumption (Azevedo 2014) and to struggle more drastically with the typical peculiarities of individuals and cultures. Thermal comfort models in the 80’s and 90’s were predominantly based on indoor air indicators (namely, temperature and relative humidity) and were particularly relevant and, even, exacerbated for air-conditioned buildings. They neglected various factors related to the occupants and their interactions with the building and the outdoor environment. Subsequently, adaptive comfort models were developed that considered other factors such as the expectation, preference and adaptation of the occupants that are managed as part of an inter-active feedback system between the building and its occupants. The adaptive thermal comfort models (ANSI/ASHRAE Standard 55 2013) are vitally important in understanding the thermal performance of free-running buildings and identifying the potential of passive design strategies, particularly where indoor comfort conditions can be achieved through passive means. Adaptive comfort models are in tune and syntonic with the passive and solar approach adopted by PLEA. Energy sufficiency and PLEA are positioned at a vital meeting point between science, technology and architecture on the path towards global sustainability. Design for sufficiency requires a more informed architectural approach from the outset that also incorporates design issues related to engineering (such as, for example, choosing of construction materials that can meet strict structural and thermal and/or air quality requirements and thus contribute towards the passive design goals). The need to optimise energy sufficiency need not constrain the creativity of informed architects, but can also support them in designing more unique solutions without the need for subsequent corrective technical interventions (de Oliveira Fernandes and Yannas 1989). It is noteworthy that analytical tools can be very useful in supporting and continuously evaluating new directions and iterations in the design process, checking solutions against engineering and other client criteria and vice-versa. Equally important are the constraints and opportunities provided by a local culture or site that can drastically influence the building’s performance and success, and should be incorporated in the architects and engineers early design decisions however apparently trivial, such as a need for quiet or privacy. The (compound?) solution for each building should be unique, rather than something that can be generalized and obtained in catalogues (de Oliveira Fernandes 1989). Energy sufficiency in buildings There are two important points to note when conceptually differentiating energy sufficiency and energy efficiency: 1. Energy efficiency and comfort As alluded above, energy sufficiency provides a better framework for incorporating both qualitative and quantitative perspectives in the analysis and calculations aiming at reducing the demand for energy (not only in buildings). For instance, it is common to find very low indoor temperatures in houses all around the Mediterranean basin (Santamouris et al. 2014; Magalhães, Leal, and Horta 2016), partly because the mild climate always favoured a culture of adaptation and frugality, therefore investing in better insulated building envelopes is less imperative than in more severe climates. With the current push for better building performance, better insulation is now mandatory, but it shouldn’t be expected for this to be necessarily translated into actual reductions in energy demand (de Wilde 2014; De Boeck et al. 2015; Barthelmes et al. 2017), primarily because, in this case, the benefits will probably be first turned into better indoor living conditions. Such actions might even favour increased energy demand in cases where people’s renewed expectations for comfort surpass the actual improvements in the building’s passive performance. None of these aspects can be easily incorporated within an energy efficiency analysis or cost-optimal calculation. In temperate climates, the correlation between building interventions and actual energy demand reductions may be weaker than elsewhere in more extreme climates, firstly because the energy needs for heating or cooling are, quantitatively, much lower than in extreme cold or hot regions, and, secondly, because of the aforementioned typically poor indoor comfort ARCHITECTURAL SCIENCE REVIEW conditions. Instead, by focusing more on aspects such as the role of passive performance, system-dependent energy needs, and the users’ behaviours, energy sufficiency should better accommodate the qualitative values and benefits of specific solutions and regulations. 2. Sufficiency as an intrinsic property of the built environment Second, energy sufficiency is not only about an explicit approach to convincing users to reduce their energy use and influence their behaviours but must mainly be about addressing modifications and adjustments in the built environment that can implicitly result in natural reductions in energy needs, even if the users are not aware of them. The latter is especially important in addressing sufficiency approaches within the building sector where the objective is to provide thermal comfort and health for the occupants with little or no requirements for technical interventions or user action such as by primarily promoting and exploring solar passive and other low-energy solutions. It should be further noted that while the concept of sufficiency here is being presented within a framework of buildings and in proximity with PLEA’s principles, it is in fact broader and pertinent to more applications, even from an energy-exclusive perspective. For instance, even within buildings, aspects such as hot water use, meal preparation, vampiric electricity use (i.e. standby consumption of unused devices), and others, can all be discussed within the energy sufficiency framework. At a larger level, urban planning as a background approach, should also incorporate energy sufficiency principles, be it in terms of rethinking accessibility/mobility, solar rights, urban sprawl and density, solar energy cooperatives, and others. Despite seeming to be clear-cut and objective, the concept of sufficiency has yet not been fully recognized by scholars or policymakers, despite the aforementioned IEA document and many other relevant publications and applications (Princen 2005; Darby 2007; International Energy Agency 2013; Stutz 2014). Many of its most relevant aspects are already well known and recognized but this knowledge is lost amid a confusion in terminology and imprecision of concepts that blurs the lines between passive and technical, ultimately drowning many of the opportunities that should have been explored. A point in case are the several academic works discussing sufficiency aspects but inaccurately attributing them as ‘energy efficiency’ measures, in an attempt to bring them within the common, misused, terminology. For instance, several papers refer to principles such as sensible selection of the location and orientation of the building and its openings, thermal protection, solar energy use, etc. as ‘energy-efficient’ architecture (e.g. (Okeil 2010; Junghans 2012; Manzano-Agugliaro et al. 2015; Chandel, Sharma, and Marwah 2016)). This is also found in texts of regulations and directives, which ends up having a pernicious impact by opening the door to the more lucrative, more lobbied for, and frequently easier to implement technical solutions, despite being known that these may not be adequate for a specific setting. In this sense, the law fails to correctly direct actions by ignoring the terminological nuances, failing to recognise and discuss the inherent differences between various options, or understanding the significant environmental impacts of not doing so. 295 In the case of temperate climates, and particularly the ones in the Mediterranean basin, the sufficiency approach shows that the building must be first designed in a way that captures the useful energy from the sun, storing it effectively, and later diffusing it back indoors with little or no need for technical systems. Of course, proper shading should be introduced to avoid excessive solar gains in the summer, giving space to thermal inertia to maintain adequate indoor temperatures during the hot days. This is made possible by the large daily thermal amplitudes and the generally low relative humidity of the air, which can provide comfort through high thermal inertia, good solar shading during the day, and ample ventilation during the night. There are many case-studies going back to the 80’s exploring these strategies, such as the example of Casa Termicamente Optimizada (CTO), in Porto, Portugal (de Oliveira Fernandes, Maldonado, and Gonçalves 1987). The PLEA approaches mainly target these sorts of strategies and many architecture examples worldwide bear testimony to that. For instance, designing small windows and doors in warmer temperate climates is one of the evident examples of solar protection in vernacular architecture. There are various such examples of small openings being used in buildings today in southern Portugal, Italy or Greece. Conversely, in colder and windy winters, even in temperate regions, enclosed balconies which can serve as buffer zones to increase solar gain and prevent the heat loss are explored, such as Beira Alta region in Portugal. Examples of patios can be found, for cultural reasons, even in the South and Central American continents, indicating how vernacular architecture has been conveyed between countries. In regions with less favourable climates, either in colder high latitudes and continental locations, or warmer/humid climates as in the tropics, it is clear that the potential for passive solutions is severely restricted. Be it because of lower solar resource availability, higher thermal losses, lower daily thermal amplitudes, or simply because outside conditions are consistently unfavourable over longer periods, the indoor-outdoor dialogue must be more contained and controlled in these more adverse conditions. Thus, the use of energy-reliant technology is generally mandatory. Thermal inertia loses much of its usefulness, and might even have a pernicious impact here, so solar gains might be limited, controlled shading might not be as essential, insulation might be essential in very cold climates but not at all in the tropics, and so on. Even so in these more challenging conditions, a better design will always result in significant reductions in energy demand, and arguably be even more significant, quantitatively, than in temperate climates, regardless of achieving near-passive performance. Furthermore, by reducing the energy needs first, the dimensioning of eventually required systems (HVAC) will result in smaller, less powerful and less expensive technical solutions, which are typically easier to install and maintain. This will bring further benefits to the national grid given the expected reductions in peak power demand and fluctuations, while also facilitating more effective use of the investments in renewable energy sources. This is essential in helping the conversion of the national energy system into a more fully renewable-based one, which can then be achieved with smaller investment and more quickly. 296 H. SANTOS ET AL. Discussion and conclusions It is known that energy efficiency focussed design approaches tend to struggle with the issues of the rebound effect, facilitating more frequent or intense use of more energy efficient devices, counting on their lower operation costs, while not actually reducing energy consumption. The result is that energy savings are generally much lower than expected and energy consumption can rise significantly. Furthermore, in addition to this ‘direct’ rebound effect, there may also be an ‘indirect’ rebound effect when an increase in disposable income still results in increased energy use elsewhere (Azevedo 2014), or even the prebound effect (Sunikka-Blank and Galvin 2012), where energy consumption (and potential benefit of energy efficiency initiatives) is over-estimated. Both rebound and prebound effects demonstrate that current predictive measures of energy consumption are inadequate as they fail to take into account how buildings are actually used by their occupants. Energy sufficiency approaches, particularly within the buildings sector, using PLEA principles, are much less susceptible to these effects. A building that is designed to be able to passively provide comfortable conditions indoors in moderate climates, will under normal conditions hardly give any justification for its occupants to resort to additional heating or cooling, if given the option to instead use whatever flexibility in control they might have to hand to fine-tune their surroundings, such as by opening windows, closing curtains and so on. The same can be said about the management of air quality in European homes that is achieved primarily by pollutant source control coupled with natural ventilation, illumination when daylight is available outside, noise that is properly controlled from nearby sources, and so on. Reviewing the PLEA approaches to design, one can conclude that they contribute to energy demand reduction through sensible design of the building itself and its adaptability to the local environment and culture. The design solutions PLEA promotes come long before any ‘energy efficient’ technical add-ons are even considered at different stages of the building energy flows (efficiency). PLEA thinking is all about reducing the demand itself by tackling, primarily, the actual energy needs (sufficiency) of the building and therefore, the PLEA concept is encompassed within the concept of energy sufficiency. The foundations of PLEA were established on the principles of passive, vernacular and bioclimatic architectures that are completely independent from the secondary additions to building of energy-consuming HVAC systems. These are the implicit approaches of energy sufficiency, but energy sufficiency is an even broader concept than PLEA as it also embraces the need to design to optimise user behaviour contributions as well. While the concept of energy sufficiency proves to be effective and applicable within the building sector, nowadays many building designers and occupants disregard potentials of ‘sufficient design’ and rely on pollution-causing and more costly HVAC options to make buildings habitable. Regulations too often provide little help in promoting energy sufficiency and in doing so fail in their roles and responsibilities in directing appropriate decisions and actions. Currently, construction firms tend to replicate the same building solutions from one country to another with very different climates, cultures and user behaviours. The current standardisation of buildings around the globe is based predominately on non-adaptive thermal comfort models, relying solely on the use of technical add-ons. For instance, in the United States, the Green Building Council (USGBC) grades buildings through the Leading in Energy and Environment Design (LEED) certification. However, this certification does not accredit bioclimatic and passive solar designs. It is noteworthy that while it is possible to get the silver grade without any improvement in the energy performance of the building, it was originally impossible to achieve a high score in Energy and Atmosphere (EA) category of LEED without using mechanical systems (Shaviv 2008). Why is there so much attention being paid to energy efficiency, and not enough to energy sufficiency? Firstly, when discussing energy and buildings at a national level the expressions ‘energy efficiency’ is used indiscriminately across the whole system to encompass a wide range of activities, technologies and solutions, thus absorbing the idea of energy sufficiency under this often-meaningless umbrella. As described above, this consequently results in bad policies and the proliferation of higher energy technical solutions. Secondly, most energy system stakeholders such as politicians and utilities are not yet prepared to accommodate the impact of energy sufficiency, which allows for better comfort with less commercial energy, as they are wedded to economic growth models that flourish better with energy efficiency drivers. Thirdly, energy efficiency is essentially linked to profitable market opportunities which would be endangered if energy demand was reduced to the actual passive building energy needs. Energy sufficiency is not a proposal from the past, but one for today and for the future. Understanding and recognising the importance of the concept of energy sufficiency can lead to the continued evolution of the PLEA ideals to more effective and much broader applications and challenges in the real life. This is a vital, pre-emptive design approach that results in reduced energy needs, improved occupant wellbeing and happiness at home and work, lower energy costs and ultimately to a more environmentally-responsible and resilient built environment. Acknowledgements This paper is based on and extends upon a conference paper by the same title presented at the Passive Low Energy Architecture Conference in Edinburgh, Scotland, in July 2017 (Samani, Santos, and de Oliveira Fernandes 2017). The authors gratefully acknowledge the funding of Project NORTE-01-0145-FEDER-000010 – Health, Comfort and Energy in the Built Environment (HEBE), co-financed by Programa Operacional Regional do Norte (NORTE2020), through Fundo Europeu de Desenvolvimento Regional (FEDER). Disclosure statement No potential conflict of interest was reported by the authors. Funding The authors gratefully acknowledge the funding of Project NORTE-01-0145FEDER-000010 – European Regional Development Fund (FEDER, Fundo Europeu de Desenvolvimento Regional). ARCHITECTURAL SCIENCE REVIEW ORCID Hugo Santos http://orcid.org/0000-0001-5331-5901 http://orcid.org/0000-0001-7843-5280 Pouya Samani http://orcid.org/0000-0002-5694-3599 Eduardo de Oliveira Fernandes References Alcott, Blake. 2008. “The Sufficiency Strategy: Would Rich-World Frugality Lower Environmental Impact?” Ecological Economics 64 (4): 770–786. doi:10.1016/j.ecolecon.2007.04.015. ANSI/ASHRAE Standard 55. 2013. “Thermal Environmental Conditions for Human Occupancy.” Azevedo, Inês M.L. 2014. “Consumer End-Use Energy Efficiency and Rebound Effects.” Annual Review of Environment and Resources 39 (1): 393–418. doi:10.1146/annurev-environ-021913-153558. Barthelmes, Verena M., Cristina Becchio, Valentina Fabi, and Stefano P. 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