Introduction

The Intergovernmental Panel for Climate Change (IPCC) recently published its Sixth Assessment Report (AR6)^[1], with the opening statement that:

Glaciers are retreating, sea levels are rising, desertification is on the increase and we are experiencing more frequent and more intense storms as well as coastal and inland flooding. This is caused by human influences; primarily through the combustion of fossil fuels and the corresponding emissions of Carbon Dioxide.

In recognition of the very real and significant risks of climate change, at the twenty first Conference of Parties (COP21) in Paris in 2015, 196 parties signed up to a legally binding commitment “to hold the increase in the global average temperature to well below 2°C above pre-industrial levels and to pursue efforts to limit the temperature increase to 1.5°C above pre-industrial levels”. The 1.5^oC threshold is likely to be reached on a temporary basis during the next five years.

Domestically, the 2019 amendment to the 2008 Climate Change Act commits the UK government to the achievement of net-zero CO₂ emissions by 2050. Achieving this target will involve a broad palette of measures, including the decarbonisation of the power sector, the electrification of heating, the substitution of internal combustion engines with electric vehicles, increases in Carbon sequestration and the substitution of fossil fuels with biofuels and Hydrogen.

According to the International Energy Agency^[2], the buildings and construction sector accounted for 36% of final energy use and 39% of energy and process-related CO₂ emissions in 2018. Urban planners, urban designers and building designers have considerable potential to make a positive contribution towards reducing the environmental impacts of buildings and the built environment more generally. Indeed, according to the United Nations, cities are likely to be home to over two-thirds of the global population by 2050, and they are already estimated to consume over two-thirds of the world’s energy and account for more than 70% of global CO₂ emissions. Not only can urban and building planners and designers contribute professionally, but we can each also make positive contributions towards limiting climate change personally.

This book, however, is very much focussed on the former, on empowering built environment professionals to minimise Carbon emissions and the corresponding risks of climate change through the carefully considered application of fundamental principles in the design of individual, groups and even stocks of buildings.

This begins (Chapter 1) with detailed explanations of the mechanisms by which heat is transferred in buildings and how this transfer of heat across the envelope of buildings can be calculated, as well as how this translates to the demand and use of energy to maintain comfortable indoor conditions. In addition to heat, moisture also flows through the envelope of buildings with corresponding risks of condensation occurring at both the surfaces as well as within constructional materials, with potential adverse health impacts. This is addressed in Chapter 2, in which the principles of air-conditioning systems and the corresponding demands for energy are also described. This leads to explanations, in Chapter 3, of concepts of thermal comfort and the associated risks with which indoor spaces may overheat (or indeed underheat). In the quest to reduce energy use and associated CO₂ emissions, the fabric of buildings and how this is regulated using automated controls and/or through occupants’ interactions plays an increasingly important role. Indeed, occupants’ behaviours and how these influence their comfort has become one of the most intensively researched subjects throughout the past two decades.

This discussion proceeds, in Chapter 4, with detailed explanations of how buildings may be naturally ventilated, to reduce the corresponding demands for mechanical ventilation and the associated energy use, using combinations of wind and buoyancy pressures. Also discussed here is how air flows around buildings and how this influences the comfort of pedestrians.

An important strategy in reducing the demand for applied energy is to effectively harness solar energy. To this end Chapter 5 explains how to calculate the position of the sun and from this how to calculate the amount of solar energy that is incident on the envelope of buildings. This solar energy can be utilised by both passive means, due to transmission through glazing to reduce demands for heating for example, as well as through active means, using solar thermal and photovoltaic collectors. It is also important, however, that excess solar energy is avoided, to reduce the risk of overheating and the corresponding demands for active space cooling. In this chapter, we also therefore discuss shading and how, with an understanding of solar geometry, shading devices can be effectively designed.

This leads naturally, in Chapter 6, to discussions of principles of daylighting in architecture, beginning with a brief introduction to lighting perception, some basic principles of optics and how these principles can be exploited to enhance daylight design, before introducing how the availability of daylight can be quantified. Technologies to enhance daylight penetration are also described, as are principles by which daylight should be integrated with artificial light to ensure that the potential energy savings afforded by natural daylight are realised. Chapter 7 then follows a similar rationale, explaining human perception of artificial light as well as technologies for the provision of artificial lighting both indoors and outdoors, and how this provision may be quantified.

In addition to being both thermally and visually comfortable, the interior of buildings should also be acoustically comfortable. The building should be designed to limit the transmission of noise and provide conditions that are conducive to the appreciation of the sounds that relate to each room’s purpose, whether this relates to the transmission and intelligibility of speech or the appreciation of music. Occasionally, the provision of acoustically comfortable interiors can be in conflict with other goals. For example, it may be thermally desirable to expose thermally massive interior surfaces such as concrete ceilings or plastered brick walls, but this can create reverberant (echoey) interiors which promote noise transmission internally and which also reduce speech intelligibility. To this end, Chapter 8 is focussed on architectural acoustics.

Chapters 1 through to 8 provide the fundamental tools by which buildings may be designed to minimise the demand for applied resources through good passive design principles, whilst achieving comfortable conditions for the buildings’ occupants. However, applied energy may still be needed for artificial lighting, for heating, for electrical appliances that are required by occupants to perform their tasks and potentially also for mechanical ventilation and cooling. Chapter 9 explains how these energy needs may be satisfied using renewable energy technologies. This involves explanations of the functioning of solar and wind energy conversion technologies, of heat pumps, biomass boilers and anaerobic digesters, combined heat and power systems and energy storage technologies, as well as how to quantify the energy that can be converted by these technologies.

This book closes by describing how the performance of buildings may also be influenced by some higher-scale considerations (Chapter 10). These include the urban climate and how this also influences outdoor comfort, local or national infrastructure and how buildings collectively influence CO₂ emissions and how these collective impacts can be modelled with a view to understanding the potential effectiveness of decarbonisation policy interventions. This final chapter closes by discussing national decarbonisation scenarios and some emerging socio-technical trends which may alter how we live our lives in the future.

This book is intended to appeal to a diversity of readers and so, with this in mind, each chapter contains phenomenological descriptions of the physical principles at play, as well as quantitative descriptions of these phenomena. For example, Chapter 1 describes how heat flows in buildings as well as the means by which this flow of heat may be quantified, and also the underlying principles of programs that model and simulate these heat flows. To help the reader navigate through this book, the more qualitative content is identified using a blue font, whereas the remainder is represented using a black font.

My aim is to progressively refine and extend this book, publishing regular updates, so that readers will have a freely accessible resource that maintains its relevance as they progress through their academic studies and into professional practice. It is also planned that an accompanying book will be written, as a collaborative project. This is intended to focus on explaining and demonstrating how these fundamental principles can be and have been employed in real building and urban planning and design projects.