www.buildingsandcities.org/insights/reviews/thermal-design-buildings.html

by Phillip Jones. Crowood Press, 2021, ISBN: 9781785008986

Jenny Crawley (UCL) reviews this book which provides a sound basis for understanding and creating low energy design solutions that are grounded in the underlying principles of thermal design.

Thermal Design of Buildings is a helpful book which explains and applies physical principles in order to help the reader understand the relationship between buildings and energy. It is broadly structured by presenting the context of climate change and net zero buildings, then the different aspects of thermal design (building fabric, ventilation, building services), followed by a chapter illustrating the application of these aspects over the last 50 years, and ending with a reflection on ways forward.

The author aims to 'provide an insight into current thinking in thermal design, with reference to its historical context, as well as signposting future developments'. Since solutions evolve, the aim is 'not to provide off the shelf recipes but to provide an understanding of the subject of thermal design, and an awareness of what is possible, from which future innovative solutions can be developed'.

The book meets these aims and fulfils its aspirations admirably. The 'awareness of what is possible' is an important inclusion, in order to ground aspirations in real physics. For example, the book illustrates the variable amount of solar radiation in different countries. This shows how difficult it would be to provide all of a building's energy from its own solar panels some countries, but more feasible in others. In addition, the reader is shown how to calculate important metrics (including certain key equations such as ventilation airflow through openings, and U-values of constructions), without being a dry book full of equations.

The book makes its points strongly and with the right level of detail. For example, there is a very valuable section illustrating that different building types have different heating/cooling and ventilation requirements, enhancing the point that each building needs a different solution depending on what is going on both inside and outside. Just occasionally there is too much detail in my opinion. For example, a table of different types of chiller compressors, which may not be in the reader's remit to specify.

Some key themes that emerge are:

• Thermal design is not one-size-fits-all, but is specific to the location of the building (and always has been through history) as well as what happens on the inside of the building
• An understanding of thermal design principles is essential for designers. The book provides a sound approach to the underlying physics - as opposed to simply presenting a list of technologies (e.g. compression chiller, absorption chiller, etc)
• Presenting typical numbers is very helpful for the reader to understand the simple potential of different options, and then dynamic building simulations can help the reader see for themselves how the different solutions might work.

These are really valuable points that the book conveys clearly. In particular, Jones successfully argues that by understanding the physical principles of the different design elements one can start to combine them in the most appropriate ways (for example, understanding how a thermally efficient building fabric can allow a low temperature heat distribution system).

The incorporation of a historical perspective on thermal design is perhaps quite novel. As well as the excellent section on vernacular architecture around the world, there is a chapter on the history of low carbon building from the 1970s and what we have learned or not learned. It also brings in the subject of fuel cost, which helps to explain why we may or may not have seen adoption of thermal design principles up to now.

The intended audience is 'those interested in sustainability and the built environment, including students, practitioners, policy makers and the public'. It definitely makes a good student text: it introduces just the right amount of physics (although a little more on thermodynamics would perhaps have been helpful) and applies it to different fabric and HVAC (heating, ventilation and air conditioning) strategies, including many helpful case studies. Some topics, like the psychrometric chart, are probably not understandable solely from the provided description but at least students are introduced to what it is and can go and read more about it elsewhere.

In addition, the book is well suited to practitioners too. It includes many useful rules of thumb and typical numbers (e.g. the typical temperature of water supplied to a chilled ceiling), then uses simulations to show more complex aspects (e.g. how much cooling a chilled ceiling can give over a day with varying outdoor temperature). This combination of helpful rules of thumb with simulations to illustrate the details is one of my favourite aspects of the book.

Some of the book is accessible is to policy makers and the public. The final chapter, entitled 'Transition', presents a reflection on wider changes that are needed in order to create an environment in which net zero buildings can get built. These include procurement, a discussion of top-down and bottom-up policy approaches, and some reflections on the way forward.

The focus of the book is design. However, a well evidenced and widespread problem in the real world is the performance gap, in which buildings are not built and / or operated in accordance with the intended design. This issue is mentioned a few times, but perhaps could have been treated in a little more depth, with examples of specific checks which can be undertaken at different stages in the design, build, commissioning and operational phases. Perhaps a further book by Philip Jones is needed to address this phenomenon.

Thermal Design of Buildings gives a holistic understanding of why and how net zero building design can and should be realised. The book is to be applauded for providing a useful, insightful and clear approach to thermal design and energy demand reduction. I certainly will be recommending it to my students as a useful resource.

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