In Jakarta, ice produced at night keeps the embassy cool during the day

Measured over a whole year, the average daytime temperature in Jakarta is around 30 degrees. ‘You need to keep cool to stay productive in this climate. It’s also extremely humid,’ Hans explains. ‘If you don’t control indoor humidity levels, your equipment will break down. Air conditioning accounts for almost 60% of the embassy’s energy consumption.’

The embassy’s air conditioning system was 25 years old and no longer very efficient. The embassy’s management and DHF’s predecessor decided that it was time for a new, more sustainable system, to be installed when the embassy was to be renovated in 2018.

Ice-cold energy system
Hans was already familiar with the concept of ice storage. Indonesia is the ideal location to opt for this form of sustainable air conditioning, because the country has one of the biggest sources of geothermal energy in the world. At night, when demand for energy is less high, the whole country runs on geothermal energy, and prices are lower than during the day. An ice-storage system powered by geothermal energy was also a better option than solar panels because, as Hans points out, Indonesia’s too hot to get a decent output from solar panels.
After some research, DHF’s predecessors opted for a Malaysian manufacturer of ice-storage air conditioning systems. These specialists had already proved themselves with systems in various large buildings in Malaysia, and wanted to expand their operations to Indonesia. Their price-quality ratio was also the best. From the tendering stage, DHF was assisted by an Indonesian consultancy. ‘It’s important to work with a local agency that knows the local market and how everything works,’ says Hans. ‘They selected five reliable contractors for us, and we invited them to submit tenders.’

Freezing and melting
The project was completed in 2019, four years on from the planning stage. With a floor space of between five and six thousand square metres, including space for cultural activities, the Dutch embassy in Jakarta is a large building. The ice-storage system now keeps it cool. At night, water stored in four large tanks beneath the embassy is frozen, using geothermal energy. During the day, a heat exchanger transfers the chill from the ice into air conditioning units, cooling the entire building. This air conditioning system reduces the mission’s CO2 emissions by 102 tonnes a year.
‘The system is fantastic,’ says Erie. ‘We haven’t had any serious problems since it was installed in 2019. A team trained by the manufacturer and located in the Jakarta area is responsible for maintenance. We can always call them if we have a problem.’ The embassy also has two other air conditioning systems: a conventional electric system and a back-up system. ‘The new, conventional system is still more energy-efficient than the old system.’

Models of sustainability
Several more sustainable improvements were made at the embassy. LED lighting replaced the strip lighting, the building now has a smart building management system and staff separate their waste, which is collected by a specialist company as public authorities in Indonesia have not yet organised separate waste collection.
The Dutch embassy is now regarded in Jakarta as a model of sustainability, observes Erie. ‘Staff from other embassies sometimes come to see what we have done,’ he says. ‘People from the Swiss embassy were recent visitors. They were pretty impressed.’

Look around you
But the plan can’t simply be copied by other embassies, Hans says. ‘You first have to investigate whether you have an off-peak period for producing the ice, like night-time here in Jakarta,’ he says. ‘And there’s little point if your electricity comes from a coal-fired power station.’ Hans is full of praise for the embassy’s senior managers. ‘Their enthusiasm is vital if a plan like this is to succeed.’
Erie also mentions the key role played by senior management. The Indonesian facilities manager advises his colleagues at other embassies to research the options before making any decisions. ‘What innovative concepts do you see locally? For us, it’s really important that the manufacturer is located in Malaysia, so that the lines of communication are short,’ he says. ‘You need to identify the most effective solutions for your embassy. We live on a tropical island, so it takes a huge amount of power to produce a cool working environment. That’s why this investment was so effective.’