Design Building physics

efficiency

D

In the low-carbon age, building services engineers need to seize hold of a discipline that helps create a truly sustainable building devoid of green bling, writes Doug King

uring the 20th century, architecture was liberated by abundant cheap energy, allowing forms of building that could not previously have existed. In the 21st century,

buildings must evolve to meet the twin challenges of climate change and energy security. In order to conserve diminishing fossil fuel supplies, we will have to cut down on waste and inefficiency. The need for genuinely sustainable buildings is

more pressing than ever; it is no longer acceptable to bolt green bling onto conventional, energy-hungry designs. Before renewable energy generation is even considered, it is vital to ensure that buildings are as energy-efficient as possible, otherwise the potential benefits are simply wasted in offsetting unnecessary consumption. The shift to a new low-carbon paradigm will require

Without

a dramatic increase in skills, the proposed acceleration towards zero- carbon new buildings by 2020 will be hard to deliver

engineers to take the lead. Building projects are traditionally led by architects or project managers, but building energy performance hardly features in architectural education. This lack of essential knowledge to inform strategic design decisions early in a project’s life has led to the perpetuation of an experimental approach to building performance, rather than an approach based on rigorous analysis, synthesis, testing and feedback. Building physics, the engineering of the building

form and materials, creates the opportunity for engineers to engage with the design at early concept stage when the critical decisions affecting passive performance are made. In order to address the root issues of sustainability,

professionals throughout the construction industry need to be well-versed in the discipline of building physics. Building physics emerged during the latter part of the 20th century at the interface between building services engineering, applied physics and building construction engineering.

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CIBSE Journal April 2010

Unique mix

Building physics investigates the areas of natural science that relate to the performance of buildings and their indoor and outdoor environments. Yet few people in the industry are presently aware of the discipline, and it is taught only as a minor part of a limited number of engineering degree courses. Building physics deals principally with the flows

of energy – both natural and artificial – within and through buildings. It covers a unique mix of heat and mass transfer physics, aerodynamics, material science, meteorology, construction technology and human physiology. The discipline complements and supports building

services engineering, formalising many aspects of the work that building services engineers are already called upon to do. Building physics provides the tools to analyse the thermal and energy performance of parts of the building not traditionally considered to be building services systems, such as the structural frame and envelope. In an industry where each product is essentially

a prototype, and when it may take years or decades for building performance problems to come to light, we can no longer afford the luxury of experimenting with the physical form of buildings. In order to create buildings fit for the 21st century, rigorous performance analysis and energy prediction needs to replace experimental building development. Systems engineering recognises that complex

products, such as buildings, require many interdependent systems to function in harmony. Building physics already encompasses architecture, structure, façades and building services, and so can provide the framework for developing a systems approach. Clients of industry and construction need clear guidance on which parties in the design team >

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