Reducing energy demand on construction sites can start with monitoring

By Tony Selwyn, head of environmental planning at Plowman Craven

Whilst enjoying an ice cream on a recent holiday, I couldn’t help but notice the idling engine of the ice cream van nearby. Not great in terms of either noise or air pollution, but essential for a large majority of vans to keep some of their equipment functioning and produce cold. In recent years some councils have started to ban ice cream vans from certain areas, with Camden Council banning them from dozens of streets due to concerns over air pollution.

This got me thinking closer to home, about the construction industry, which requires a huge amount of energy – especially on site where the delivery of large, complex projects can span years – resulting in significant carbon emissions. How can we drive energy efficiency while ensuring adequate supply of power?

Contractors have traditionally used damaging energy sources to power sites or combustion engines for non-road mobile machinery. While electricity is an efficient alternative to fossil fuels, relying on a diesel-generated supply is not only expensive but also a major emitter of harmful pollutants. The pressure on the grid is also significant and connections can be challenging.

It’s not sustainable in the long term, and policy is evolving accordingly. To ensure the highest clean air levels in the capital, the London Plan stresses the need to comply with legal limits on nitrogen oxides and to reach World Health Organisation guidelines for particulate matter. These targets are trickier to meet, as this means cutting previous values by more than half. It also means cleaner energy and greener sites are no longer a ‘nice to have’ but non-negotiable as policy will only become more stringent in the coming years, making it more difficult for building sites to use certain types of kit.

There is much discussion of turning to renewables but one element that hasn’t yet been widely demonstrated is the considerable scope of the monitoring process to reduce energy demand earlier on and contribute to more sustainably run sites. For instance, at Plowman Craven, in the past year we carried out noise, air quality and dust monitoring using an off-grid system for the entirety of a six-month project on a construction site in London.

Lessons from an off-grid monitoring project

Our team was in a unique position, given that there was no mains power connection at all available on site and the client asked us to find an alternative solution. Ordinarily, the easiest and cheapest option would be to use a generator but we were conscious that using a generator on a site like this would detract from the point of monitoring for air quality because it emits particulates itself. We therefore looked at using a hybrid PV and wind off-grid system, with the energy collected powering a back-up battery.

There were some hurdles to overcome. The system didn’t provide consistent 24/7 power since on cloudier or less windy days we were still overly reliant on the battery. We also faced severe weather during the project when, in February 2022, the UK was hit by three major storms in just a week with winds of up to 70mph. This caused some of the kit, which was secured and mounted on a tripod, to be blown over and damaged. Despite these teething issues, we still delivered on deadline and to budget, meeting the client’s objectives.

Some barriers to entry may be that the kit is expensive, with a longer lead time for orders and delivery, and teams may need some training to be able to install and use it effectively. We took this route because we didn’t have any other choice but to innovate – this was our first time using this system but it proved a valuable experiment that paid off.

We have seen first-hand that the off-grid method can work, but more research is needed to finesse the process, make the systems more robust and encourage wider industry uptake. We would certainly use it again but would try to work with the supplier to enhance the kit, making it more sensitive and efficient in how it collects and converts energy to ensure a reliable flow of power. On particularly windy days, for example, it’s about capturing as much wind as possible to be used later, to really maximise the system’s benefits.

For the type of monitoring we were doing, such systems are not commonly used, with few suppliers who can provide off-grid systems at scale for the wider construction industry. However, the market is developing. With climate change, the energy crisis and tightening environmental regulation, these systems will come to the forefront and become smaller and more efficient, sensitive and sophisticated. At this stage suppliers need feedback based on real-life use to see where small tweaks can improve the products. As they mature, the systems will also become more economically viable and attract more users. We showed it can work but it needs patience and collaborative effort to become more mainstream.

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