SPECIAL REPORT: With summer just around the corner it’s time to start thinking about what the warmer weather means for our buildings. There’s load shifting and peak demand management to master, and for tenants, dressing appropriately is key. Industry leaders are even providing cool rooms to concentrate and warmer ones for creative meetings.
Summer is on the way and we’re in for a stinker. Data from the Bureau of Meteorology shows that daytime temperatures are very likely to be above average over virtually all of Australia during the October to January period.
Summer brings a couple of challenges for managing energy in non-residential buildings. Firstly, keeping buildings cool enough uses a lot of energy and can lead to skyrocketing energy bills and emissions. The ultimate goal is to keep energy use down while ensuring occupants aren’t left hot and bothered.
Secondly, this extra demand puts pressure on the grid and increases the chance of blackouts and brownouts. The influx of renewables has created additional challenges for managing the grid, with solar generation during the day dropping off just as demand spikes in the evening when people return home to cook and turn on their airconditioning units.
The good news is there are a number of tactics buildings owners (and homeowners) can employ to keep energy use in check over the summer months.
Energetics general manager, clients and business development, Andrew Tipping says the first practical step for any building owner in the lead up to summer is ensuring cooling plants and other equipment is running optimally. The same applies to back up generation equipment.
He says building managers should also consider shaping the load to better suit price signals. This involves taking advantage of the huge oversupply of solar during the day when the prices are at zero or negative.
“If you can change your load profile when generation is cheap then you can save money.”
Building owners will need to think about shaping the load profile across entire building portfolios, Tipping says, and securing an electricity agreement that reflects the load shape risks.
Tactics to manage load will change according to the weather forecast, day of the week and other variables – most of which Buildings Alive co-founder and chief executive Craig Roussac and his team have spent more than 10 years modelling to arm building managers with the tools to iteratively drive down energy usage.
Roussac says there are endless opportunities to tweak building settings to meet the weather conditions and other variables. The goal is to keep overall energy use down but also manage peak demand to keep capacity charges in check.
On top of consumption charges, industrial and commercial energy users pay capacity charges.
This fee is calculated based on the highest peak in power consumption over a short time period over the past 12 months, and is designed to help utilities generate enough supply to serve all customers. It means that simple tactics to keep energy use down during a peak demand event – AKA a stinking hot day – presents a big opportunity to decrease power bills, even if total energy consumption remains constant.
This charging structure is also unforgiving to mistakes. If a business has a peak demand of 50kW because a chiller was left on full blast for just one hour on a single day in a year, they may receive a daily demand charge to use up to that level for a whole year.
Managing energy demand in the hot weather
If building owners can anticipate a hot evening, then they can manage demand so they don’t use amounts of energy when everyone else needs large amounts.
This might involve turning on the chillers earlier than usual, before dropping them back when the peak demand period starts in the middle of the day.
Roussac says overnight conditions are a big driver because they dramatically determine thermal loads in buildings.
A night purge, which is the removal of heat from a building by bringing in cool night-time air without the use of active HVAC cooling and ventilation, is another option during a hot spell. This is commonly done after a hot weekend when the building has built up a large thermal load.
During a peak heat event, building managers might also automate demand response mechanisms and ask tenants to turn blinds down.
“Every building will have its own unique strategy and attitude to prepare for a peak event. “
The accompanying graph from Buildings Alive shows the electricity demand profile and internal temperature range in a Melbourne shopping centre on a hot 40 degree plus day.
It shows that measures such as increasing the “deadband” (letting the internal temperature rise a little higher than normal, which shoppers prefer as it’s less of a shock going from the hot outdoors to chilled indoors) and turning airconditioning units on one-by-one in the morning.
These actions led to a 580kVA lower maximum peak demand than the highest peak over the previous year, resulting in electricity savings of $5344 a month by maintaining peak demand below 2434kVA.
Buildings are like batteries
Solar energy production peaks at mid-day and this causes demand for other energy to drop off. But in the evening solar production drops off and demand increases as people return home and start cooking and turning the airconditioning on.
“You should therefore be trying to match load to generation and shift work with electricity to times that electricity is being generated.”
Roussac says it’s possible for buildings to behave like batteries by blasting the airconditioner while solar is generating during the day. Done correctly, this pre-cools the building enough to allow airconditioning to be turned off or on low during the peak late afternoon period.
“That’s a battery without all the environmental issues of batteries. We should be thinking of buildings as batteries.”
Roussac says load shifting strategies can shave up to 30 per cent off energy bills. Similarly, this has the potential to cut demand on the grid by about a third and reduce the threat of blackouts.
But not enough people are thinking about the bigger picture
Energy savings for individual buildings is a great outcome but there’s also a huge opportunity to make the grid more reliable.
“The interesting question for Australia and all advanced economies is trying to coordinate this stuff – managing your own demand but also focusing on the grid issues.”
But Roussac says most building managers aren’t thinking about the grid.
“The next big question is, can that be harnessed economy wide – that’s something we haven’t nailed yet.”
He said with adequate warning of high demand periods and incentives to shift loads then “billions of dollars worth of batteries don’t need to be purchased.”
Many building managers don’t have the right information
Mistakes in build energy management can cost a lot. If equipment is accidentally left running during a single peak demand period, this can add thousands onto energy bills.
That’s why it’s so important to nail energy optimisation during those stinking hot days and have enough warning to prepare.
Too often building managers aren’t getting the information they need to work out what strategies work best to manage a building’s load during a peak event.
Many building owners are flying partially blind and are only able to guess from their monthly bill if their adjustments were effective.
Dress for the weather – leave the cardie at home in summer
Tenants are the other part of the equation. There’s a huge opportunity to keep the temperature closer to the outdoor temperature, rather than cooling a building to a crisp 22°C on a 35°C-plus day. In offices, it’s not uncommon for people to bring jumpers to work in the middle of summer because it’s so cold inside.
This is largely because tight temperature ranges are written into leases. The standard lease will see commercial office buildings in Australia maintain a fixed temperature of 22°C each day of the year.
According to CitySwitch sustainability engagement coordinator Zoe Baker and City of Sydney sustainability engagement manager – office Kimberly Camrass, this 22°C setpoint figure is based on one set of data from the 50s when offices were occupied almost purely by men in suits.
Allowing slightly higher temperatures is the ultimate low hanging fruit in building energy efficiency. Baker says that expanding an office deadband by 3°C can cut HVAC energy costs by up to 30 per cent and make a sizeable contribution to emissions targets.
Tenants have the option of signing a green lease that allows for temperature adjustments in line with occupant needs and the latest science.
The Better Building Partnership has green lease templates available.
Adjusting the temperature deadband is a tricky issue
As well as the lease issue, Baker says there’s not a lot of incentive to widen the temperature deadband because people don’t want to be told that they’ve been made to feel less comfortable to save money.
She says the message will be better received by occupants if they focus on the benefits to the tenant.
CitySwitch currently has a pilot program underway that addresses some of the barriers to widening the temperature range. The Better Buildings Cup brings together 14 of Australia’s largest buildings, 150 companies and their teams to compete for the title of “Australia’s most sustainable building”. Lendlease, AMP Capital, WeWork, Arup, KPMG, Westpac and LinkedIn are some of the companies involved.
There’s four components to the program and one of them is “bring your best self”, which involves preparing for the warmer months.
The program encourages people to dress appropriately for the weather, and has come up with campaign posters that encourage people to take off their jackets when it’s too hot, among other tongue in cheek messages.
Cool for intense work, warmer to let your creative spirits flow
The program also calls for a diversity of spaces and activity based working arrangements, with the latest research finding that cooler, quiet rooms are best when you need to concentrate hard on a single task, but slightly warmer rooms are better for creativity and collaboration.
At the heart of the campaign is making occupants realise they have control over their own comfort, and that there are strategies they can employ before asking for a change in temperature.
There’s some evidence to suggest that people are content just to have a say on the temperature. An experiment that allowed users to comment on the comfort of an area through a digital platform had an effect on perceived comfort even though no adjustment to the temperatures were made.
Tenants can also play a role in load shifting. One emerging model is switching off the airconditioning at 6:30pm in all but one floor for workers burning the midnight oil.
CitySwitch launched the toolkit for preparing better comfort conditions at the start of the year, and has plans to push it out in December to the building managers who are part of the Better Buildings Cup program.
Baker says the program is important because it gets all the tenants in a room with building managers to make decisions about energy use.
“Building managers are not sustainability professionals or engagement professionals – I’m there to herd the cats into the room together.”