Whole Life Thinking - David Arnold responds

President George Adams wonders whether lawmakers are doing their bit in responding to and mitigating the consequences of climate change. He points out the law, both national and international gives permission to governments, organisations and investors to take from the earth's resources but does not have a provision to create a balance that prevents the potential worst effects of climate change. This led me to think of the part building services engineers can play; we aren't lawmakers but how we can best contribute to achieving this balance and how we should best try to influence legislation?

Clearly building services engineers play an important part contributing to achieving this balance by designing services installations that minimise energy use. However we usually think of minimising emissions as simply improving the operational efficiency with the ultimate goal of “Zero Energy Buildings”, i.e. zero net energy consumption and zero carbon emissions annually. The zero net energy consumption is, however, based on annual inputs and outputs and only reduces the emissions from new buildings. This focus on achieving zero-energy buildings, based on annual inputs and outputs, has I believe distracted us from the “Whole Life” aspect of minimising emissions.

We know that the rate of replacement of buildings is low, typically around 1% of all buildings per year for developed countries. Given that the current horizons for reducing energy use extend to 2050 the majority of today’s buildings (and in some cases the mechanical systems), estimated at up to 80%, will still be in use at that time. Zero energy buildings, whilst an important goal, will not be the whole answer to achieving the contribution from buildings to the legally binding target of the 2008 Climate Change Act, i.e. reducing the UK’s greenhouse gas emissions by at least 80% (from the 1990 baseline). Whilst not ignoring the part energy efficient design plays in new buildings, I believe greater additional reductions in emissions in the medium future can be achieved by turning our attention to the energy use and embodied energy in our stock of existing buildings. A recent blog by Mark Bowers of Arup called the embodied energy of buildings their “hidden assets”, quite appropriate.

Cole and Kernan carried out one of the few published analyses of the “Life Cycle Energy Use in Office Buildings” that incorporated embodied energy as long ago as the mid-90s. They concluded that embodied energy associated with replacement and repair of building elements over the life of a building is greater than that associated with any single element of the initial embodied energy. For a current typical building life of, say, 50 years, the recurring embodied energy (between 6.5 and 6.8 GJ/m²) is equivalent to the initial embodied energy of the building. The building services and interior finishes and components are the most significant categories of recurring embodied energy.

Increasingly nowadays there is an awareness of the energy embodied in the building; when it is constructed, and the services when they are installed during construction and replaced at various intervals throughout the life of the building. Assessing the “Whole Life” embodied energy in buildings is complex. Data bases for the embodied energy of building materials have been developed in recent years but provide little assistance for building services engineers attempting to minimise the life cycle energy use of comparative engineering solutions. Clearly if we can extend the reliable life of service in buildings and reduce the number of times they are replaced in the life time this will have a significant benefit.

When a building services engineer is confronted with the question, is it better to repair and retain air conditioning systems, installed say 20 or 30 years ago, or to install a new state of the art VRF system the easy answer is throw away the old system and install a new high efficiency one. This however disregards the loss of embodied energy in the original system and the embodied energy in the replacement. We should be promoting research to develop a data base of embodied energy in services plant and equipment and developing innovative tools to allow us to carry out analyses of the life time energy use of alternative repair or replace solutions.

Surely the starting point for this is for the principle of minimising embodied energy in both existing and new buildings to be introduced in the Building Regulations. This is legislation we have, can and should influence.

David Arnold is a Partner at Troup Bywaters and Anders providing troubleshooting and services as an expert witness. David shares his wealth of engineering experience as a Royal Academy of Engineering visiting Professor at London South Bank University. David is also a past president of CIBSE.


  1. David, this is a valuable analysis in a technical sphere. The interesting part is when we consider economics and the assumption that endless growth will always finance the latest, most efficient technology. It is also a commercial sphere and this forum is perhaps insulated from the reality that fuel poverty has increased dramatically, estimates now run at 40%. Perhaps this discussion ventures that the Green Deal Effect will also come to influence the commercial sector where CIBSE resides. I suggest that restraint in comfort conditions and even essential maintenance are becoming the unavoidable outcome, not only on carbon analysis, but because of the cost of financing energy efficiency improvements and supporting the rapidly-obsolescent technology in years to come. The next ten years will be nothing like the last ten. Many of our assumptions and values are going to have to change. In fact we agree here David, the key is that CIBSE needs to lead to rational needs-must approach to resource use, despite the burn-the-furniture outlook intended to keep the financial boilers going.

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