District Heating in Copenhagen

Wednesday, February 17, 2021

That’s hot! District heating is the sustainable energy trend that allows us to become carbon neutral

Isn't it ironic that heat, being the single largest energy use in the world, is a major co-culprit when it comes to global warming?

Emissions from heating water, homes and industrial processes account for over half of all energy demand globally. And it’s our cities that consume the largest part of that energy. Considering that within 30 years, 70% of the world population is expected to live in urban areas it’s clear that we are faced with a serious challenge. Switching to renewable energy sources will solve about half of the problem, but energy efficiency is just as important.

The goal is clear. The EU green deal commits to a completely carbon-neutral Europe by 2050. And while most cities struggle to stick to that deadline, Denmark’s most populous city of Copenhagen might reach the finish line a whooping 25 years ahead of the game. Their secret? District Heating.

What exactly is district heating?

District heating is a system that distributes heated supply water generated in a centralized location, to a network of residential and commercial heating requirements (such as space and water heating). After transferring its heat to the water and space heating system, the water returns to the district heating plant, and so it continuously circulates in an endless closed network of pipes. So instead of everybody having their own heating system, we share one system. There are many advantages to district heating, but the most important one is its sustainable character. District heating plants make use of renewable energy to heat the supply water. In Denmark, 30% of heat comes from burning waste like plastic bags or food containers, stuff that can’t possibly be recycled otherwise. But they also reuse waste heat from production processes.

Future proof cities

Sounds great right? It is, but as always the costs come before benefits. In the short term, implementing district heating requires huge investments, both monetary and logistic. To lay down a district heating network you’ll need to open up roads, dig large holes and implement huge pipes. Although temporarily, this is bound to have a major impact on a city’s infrastructure.

Once installed however, district heating is one of the puzzle pieces of a future proof city. Not only is it compatible with the renewable energy sources of today (biomass, wind energy, water energy, solar energy, geothermal energy etc.), the flexibility of district heating allows us to switch to future energy sources fast. So as more environmentally friendly alternatives are discovered, we will be able to utilize them centrally. Linking complete districts to sustainable energy at one, via the existing structure of district heating pipes.

District heating offers the city’s inhabitants some nice benefits on a personal level as well. Splitting the bill reduces the costs for the community. And the energy supply can be much more efficient thanks to smart electrics. Systems like Wavin’s Calefa, a centralized heat interface unit that provides heating and domestic hot water to an entire housing complex, ‘learn’ from our energy use behavior. Once the system knows what time your alarm goes in the morning, it will anticipate by sending warm water to your home and then close down the supply when you go to bed at night. Energy storage is another smart feature that comes with district heating. In summer time you might collect and store the energy you don’t need when temperatures are high, so come winter you’re all set.

Good for your wallet, great for the world 

The reason Denmark is heading towards that carbon-neutral milestone so rapidly has everything to do with 50% of the country being connected to district heating.

With systems such as district heating that quite literally connect a community, we move towards creating livable, lovable and resilient cities. Fighting global warming was always going to be a joint effort.