The climate crisis and the Covid-19 pandemic have created a perfect storm, changing people’s attitudes to offices and focussing the industry on radically rethinking how buildings consume energy and how they are ventilated.
I’ve been a building services engineer for 40 years. Throughout that time, the services in offices have been a by-product of how the buildings are designed and used: they’re often, essentially, glass boxes that face the sun and are packed with people and equipment. In fact, they’re usually more densely packed now than in the past. When I started work, we had larger L-shaped desks to accommodate deep monitors. Today with flat screens, bench desks can be as short as 1.2m, allowing you to squeeze more in. This approach has demanded buildings be cooled using space-efficient chilled water systems, and therefore sealed with a minimum of fresh air brought in for ventilation.
Getting smarter with building designs to meet LETI targets
Every time building regulations changed over the years, people found new ways of having essentially the same floor-to-ceiling glass designs – such as specifying innovative glazing. But that approach has reached the end of the road. The London Energy Transformation Initiative (LETI) targets an energy use of 55 kWh/m2/annum for office buildings if we’re to achieve net zero. Today, a typical office building uses four times this amount, so we’ll have to get a lot smarter about how buildings are designed – using less glazing and providing more shading – as well as about how they’re supplied and serviced.
We can do things like reducing general levels of lighting in favour of task lighting and making use of the fact that modern devices such as tablet computers last a whole working day on a single charge. Will there be the same need to supply everywhere under the floors for people to plug in computers if they’re using devices with batteries lasting 10-11 hours? If you do need to charge your device, you could collect a ‘power toaster’ battery pack from reception and use it at your desk – a solution that’s also more convenient than being tethered to the mains when you want to move around the office.
And we can use smart technology – such as location-based services to understand how many people are in which areas of a building and tailor services to that demand in real time. Today, systems are often continuously on the same settings throughout a building no matter what the demand. But if the building becomes the butler, as a colleague of mine put it, energy is used only when it’s really needed and there’s less waste.
Using fresh air for free cooling
The most critical thing, though, is fresh air; with the UK’s temperate climate, it provides the free cooling needed to achieve the LETI target for over 80% of the year and creates healthy environments inside buildings. While openable windows have some advantages, getting fresh air consistently deep inside buildings requires mixed-mode underfloor air systems.
Clients are embracing this approach, which can be retrofitted to existing buildings. Although the plant takes up four times the space required for a chilled water system with minimal ventilation, there is space available. Most buildings have a 600-700mm ceiling void in which the chilled water system is fitted. As this would become redundant, that space would be freed up to create instead an under-floor void for the air system. Ideally, each floor would have its own air plant but if there are concerns about air quality at or near street level, shafts can be used to draw air in from higher up. Packaged units, which open heat pumps up to the façade when conditions are right and close them off when they’re not, are also now becoming available.
Demand from occupants driving change
We are seeing growing interest in rethinking how buildings are serviced, in part because of demand from occupants. A generation of office workers is concerned about the climate crisis, and many have spent a year experiencing the flexibility and freedom that working from home can bring. In our own business, just 2% of people said they would like to go back to working five days a week in the office.
It’s likely that, in the future, offices will become places to meet with colleagues and discuss ideas, rather than places to sit and work for hours on end. Releasing our buildings from being sealed up against the outside world and moving them from chilled-water cooling to all-air systems that respond to the climate will ensure they’re fit for a net-zero future of flexible office working.