No 10 Downing Street is among the UK's most recognisable buildings. The prime minister and his ministers enjoy being photographed on the doorstep, but inside it's very much a working office space. As with any other commercial property, the building and the 150 or so staff that work there have a significant energy footprint. On an average working day, the PM's residence, plus neighbouring houses numbers 11 and 12 use around 25,000kWh, with a carbon impact knocking on 13,000kg. Total cost: £2,123.

The numbers for the 300-year-old, 6,631-square-metre property are stark, and demonstrate a clear financial – as well as environmental – incentive for energy efficiency. But how should such efficiencies be realised? According to Sarah Summerson, manager for Breeam In-Use, a building-related energy-certification scheme, there's a balance to be struck between those who use the energy and those who manage it.

Getting occupants to go green

From a user's point of view, turning off your computer at the end of the day or switching off the lights when you leave a room directly affects a building's overall energy consumption. Individually, such actions may seem trifling. Multiplied by 150 – or by many thousands in the case of the central government's total estate or a large company – these energy bills (and their carbon impact) soon tot up.

The Breeam In-Use audit methodology is designed to map a building's total energy profile, from the materials in the bricks through to the printers in the back office. Among the factors taken into account is how the property manager or tenant engages individual staff in their energy-efficiency strategy, thus providing an incentive to get them on board. Furthermore, Summerson explains, the certification process includes very "activity-specific" recommendations of improvements building occupiers can make. Among the steps taken by No 10 following a recent Breeam In-Use audit, for example, was the introduction of motion-censors in meeting rooms to regulate the lighting, power factor correction equipment, modern condensing boilers and compact heat exchangers.

RWE npower goes even further. The UK electricity provider, which has a 38% energy-intensity-reduction target for its portfolio of 26 offices, runs an extensive internal communications campaign, including periodic energy-awareness days across all its sites, as well as energy-efficiency tips on posters and via email. The power company also runs a Green Champions initiative that sees selected volunteers encourage their colleagues to adopt greener behaviour patterns.

"We use the acronym 'Easy' in our internal communications – Environment, Action, Sustainability, and You. It's been a very powerful way of attaching a branding and a logo to everything we do around engaging our staff on energy efficiency," says Jonathan Hulbert, npower's energy manager.

At management level, npower sets specific energy targets for each of its office buildings and tasks a senior manager at each site with ensuring these are met. These targets are then built into that manager's personal performance appraisal. Last year, npower succeeded in shaving £740,000 off the cost of electricity, which it sources from the retail part of its business (which itself has more than 50 renewable projects under the RWE Innogy brand, including 661MW installed capacity of wind power).

Yet employee engagement is as much about releasing innovation as about cracking the whip. With that in mind, npower runs an internal competition to generate bottom-up ideas for energy saving. Through this Future Leaders scheme, an employee in the company's Solihull offices recently proposed replacing out-of-date timers in the staff carpark with infrared motion detectors. It is now looking to roll out the solution to other sites.

Automation replacing agency

Important though employees are in reducing energy consumption, building managers are increasingly looking to automate energy systems that reduce the role of human agency. Why continually remind individual employees to turn off the air-conditioner at the end of the day, for example, when the entire heating system can be regulated centrally? This plays into sustainable energy expert Prof David Mackay's argument about the myth of the 'every little helps' theory. In short, if everyone does a little, the result still remains a little. By passing responsibility for energy use from multiple individuals to a single, stand-alone system, the opportunity for a large step-change becomes possible.

"We are getting to a point with our buildings where our staff have very little effect on our overall energy consumption. We've put an integrated building management system into almost all our sites now so that at the click of a button I can change the time the air-conditioning goes on in all the buildings or what time the lighting goes on," observes Dave Horton, npower's property sustainability and capital investments manager.

UK property developer and management firm British Land is moving towards a similar position. In the past, energy consumption used to be split pretty evenly between landlord and occupant, says Justin Snoxall, the company's lead on sustainability issues. Thanks to the introduction of automated building management systems, the balance is more like 65% landlord to 35% occupant, he estimates. The big wins for landlord-led centralised software centre on heating and cooling, which typically comprise between 20% and 35% of a commercial building's total energy use.

Further reductions can be achieved by the installation of advanced control systems, which optimise the performance of the individual components of a BMS, such as ClimaPRO, a chiller-plant system manager. "These can result in an additional 10% to 20% energy saving in a building", says Steven Shepherd, general manager of Climaveneta UK, a leading provider of climate control systems. He added: "This solution integrates the BMS, taking specific control of central units, pumps and cooling towers, ie the so called 'chiller plant', optimising its operation thanks to dedicated algorithms. Besides energy savings, it provides additional advantages in terms of predictive maintenance."

The dream of a fully automated energy system is not quite as easy as it sounds, however. In most multi-let properties, for instance, individual occupiers often run independent power systems for critical functions, such as trading floors or data-storage facilities. Some occupiers also install their own building management systems or exercise an option to override the building's central system. Engagement between the property owner or manager and an occupier's own building engineers is therefore vital, says Snoxall: "If they don't communicate with one another they create all sorts of conflicts in the system."

In its role as landlord, British Land has also taken the step of stipulating operating hours for all its commercial buildings, with lighting and heating automatically coming on at set times. Furthermore, it is installing smart metering in most of its new mixed-occupancy buildings, which enables it to identify how much energy each occupier is using. It can then charge them accordingly, rather than dividing up energy costs equally among all tenants as before.

Giles Bristow, head of energy at Forum for the Future, a London-based environmental non-profit organisation, is wary about taking office workers and other individuals too much out of the equation. For starters, building management systems are not infallible. A faulty light sensor or broken thermostat can easily throw the system and cause anomalies. As importantly, engaging employees to adopt energy-efficient behaviours at work increases the likelihood of them adopting similar habits at home. "If it's all fully automated, then you're not embedding behaviours that someone is going to take elsewhere", he argues.

Credits

This content is brought to you by Guardian Sustainable Business in association with Climaveneta. Produced by Guardian Professional to a brief agreed and paid for by Climaveneta. All editorial controlled and overseen by the Guardian.