Existing buildings are the key to meeting carbon targets

Solar panels
Adding renewable energy to a building as part of its refurbishment will reduce carbon emissions. This solar-thermal water-heating system is at Daneshill House in Stevenage.

If the UK is to meet its emissions targets, the refurbishment of the existing building stock has a vital role to play. Ant Wilson takes a look at the key considerations

When it comes to helping the UK meet its carbon emissions targets it is clear that building-services engineers have a very important role to play. It is also becoming increasingly clear that this role will have the greatest impact through refurbishment of existing building stock and that there needs to be tighter integration between services and structural disciplines.

This is in contrast to early energy-saving initiatives that put a strong focus on the performance of new buildings. The fact of the matter is that most new build is adding to the total number of buildings, rather than replacing badly performing existing buildings. In the domestic sector, for instance, there are plans to build seven million new dwellings by 2050. Even if the goal of carbon-neutrality for all new homes by 2016 is achieved, this is only preventing the situation getting any worse.

The same is also true for the commercial sec­tor, where many buildings in use today are still going to be in use 30 years or more from now. All of which explains why our emphasis needs to switch to refurbishment — if it hasn’t already.

To that end, there are several drivers that building operators are responding to. Energy Performance Certificates and Display Energy Certificates are certainly having an effect, as is the need to be ‘seen to be green’.

Major supermarkets chains, for instance, are all vying to have the best environmental performance because this may influence their customers. Universities are also finding that student choices are influenced by green issues.

Similarly, developers and landlords are finding that efficient building performance can increase their chances of letting a space, so it becomes financially attractive to invest in improvements, rather than have space lying empty while still attracting business rate charges.

From a legislative point of view, the consequential improvements embedded in the current Building Regulations also have an effect. There has also been a suggestion that future Building Regulations will strengthen this requirement, though it is as yet unclear whether this will happen.

It is also worth mentioning that some people try to avoid making improvements on the grounds that their building is listed or has heritage status. The reality is that there are many improvements that can be made to insulation levels and central plant that will not ‘unacceptably alter the character or the appearance’ of the building.

So, with this focus firmly in mind, is there an ideal approach to refurbishment?

I would say that we need to look at every aspect and every stage — the fabric, the central plant and distribution services, the controls, the commissioning and ongoing operation and maintenance (O&M).

Royal Institution
There are usually plenty of opportunities to refurbish list buildings such as the Grade 1 listed Royal Institution of Great Britain to reduce energy consumption.

The place to start is with behavioural change to achieve the quickest and most cost-effective wins, followed closely by attention to the fabric.

While the fabric may often fall outside the remit of the building-services engineer, improvements to the thermal performance of the fabric will influence the possibilities for the services. For instance, reducing solar heat gains may open the door for chilled beams rather than fan coils. Or better insulation may facilitate use of lower flow and return hot-water temperatures to make better use of condensing boilers and heat pumps.

It is also the case that many of the quick wins that building operators are looking for are delivered through improvements to existing services. Upgrading lighting to more efficient sources with better control offers relatively fast paybacks, as does the installation of variable-speed control on pumps and fans. Equally, major savings can be achieved by reducing heat gains and losses from distribution systems by better insulation of pipes and ductwork.

Where central plant is replaced it is important to follow the Building Services Compliance guides for each type of kit. Appropriate controls are also important to ensure the plant performs as well in reality as it does under test conditions. Testing, adjusting and re-testing should therefore be an essential part of the commissioning process.

There may also be opportunities to introduce renewable energy sources during refurbishment, and the current proposed feed-in tariffs actually make this more viable for refurbishment projects than for new build. For example if a photo-voltaic installation of less than 4 kW saves 10 p/kWh, the payback may be 60 years. However, if an additional 36.5 p/kWh is provided as a grant, the whole return on investment calculation changes radically.

Of course, the onus does not lie entirely with the construction disciplines. The building operator also has a role to play in ensuring efficient maintenance — from cleaning filters and luminaires to regular servicing of plant — to maintain design performance. Here again, though, the building-services engineer can help by providing detailed, accurate and easy-to-follow O&M information.

When all of these factors are taken into account, it is perfectly possible to make major inroads into the carbon emissions resulting from the built environment. The fact that it is all common sense means there is no excuse for failing to deliver those benefits.

Ant Wilson is a director of AECOM.

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