Buildings as Energy Machines: When Buildings Become the Grid
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We spend a lot of time talking about how to produce more energy.
More wind farms.
More solar fields.
More infrastructure feeding electricity into national grids.
But what if part of the solution is already sitting right in front of us? Because the reality is this: our buildings are full of energy. We just waste most of it.
Across offices, hotels, hospitals, and data centres, enormous amounts of heat are generated every single day. Ventilation systems blow it away. Cooling systems spend electricity to remove it. Mechanical systems operate in isolation, unaware that the building next door might need exactly the energy being thrown away.
So perhaps the more important question isn’t how do we produce more energy?
It’s this:
How do we stop wasting the energy we already have?
In our recent podcast episode, we spoke with Nicolas Kastbjerg, CEO of Energy Machines, about a different way of thinking about building energy systems. One where buildings are not just consumers of energy, but active participants in the energy system itself.
Or put simply:
Buildings as energy machines.
In the following article, we’ll discuss:
- Buildings don’t just consume energy. They can produce it.
- Three examples of hidden energy waste
- The regulatory challenge
- The future: decentralized energy networks
- A simple question for the industry
Buildings don’t just consume energy. They can produce it.
Traditionally, buildings have been treated as endpoints in the energy chain.
Energy is produced somewhere else, a power plant, district heating facility, or grid connection, and delivered into the building where it is consumed for heating, cooling, lighting, and operations.
But that model is starting to show its limitations.
Energy Machines operates on a different principle: buildings should be treated as part of the energy infrastructure itself. Instead of only consuming energy, buildings can:
- Capture waste heat
- Store energy for later use
- Redistribute excess energy
- Feed surplus back into local networks
In other words, buildings become small, distributed energy hubs rather than passive consumers.
This shift is especially important as energy demand grows across Europe. Data centres, manufacturing facilities, and electrification are all increasing pressure on national grids.
Large, centralized power plants will still be necessary. But localized energy production and redistribution may become just as important.
And buildings sit right at the centre of that opportunity.
Three examples of hidden energy waste
One of the most striking insights from the conversation is how much energy is quietly wasted inside buildings today. Not because technology doesn’t exist. But because systems are rarely designed to work together.
1) Hotel ventilation system
Take a typical hotel ventilation system as an example.
They usually recover around 70–75% of the heat from exhaust air. That sounds impressive. But it still means 25–30% of that heat is simply blown outside.
Energy Machines has implemented secondary heat exchangers on projects to capture much of that remaining energy and feeds it back into the building’s system.
A relatively small investment that unlocks energy that was previously lost. Multiply that across thousands of buildings, and the impact becomes enormous.
2) The data centre paradox
Another example highlights how fragmented building energy systems can be.
Nicolas described visiting a building where the top floors struggled with heating, while a data centre on the lower floors was spending a lot of electricity to remove excess heat.
The building had both:
- A heat surplus
- A heat shortage
At the same time.
The problem wasn’t energy supply. The problem was silos. Each tenant operated independently. Each system solved its own problem. No one looked across the building to ask a simple question:
How can we help each other?
This type of inefficiency exists everywhere. Data centres, office buildings, laboratories, and industrial facilities all produce enormous amounts of excess heat.
But because buildings are not designed to redistribute that energy, it simply disappears into the atmosphere.
3) Using the ground as a giant energy battery
Energy Machines also incorporates geothermal storage into systems. Not as a primary energy source, but as a seasonal battery.
The idea is simple.
During summer months, many buildings produce excess heat they cannot use. Traditionally that heat is discarded.
Instead, the system stores the heat underground. Six months later, during winter, that stored energy can be retrieved and used for heating.
This approach transforms energy that would otherwise be wasted into a valuable resource. And importantly, it doesn’t rely on futuristic technology.
It simply requires rethinking how we organize existing systems.
The regulatory challenge
If the technical solutions exist, why isn’t this approach everywhere already?
Part of the answer lies in regulation.
In Scandinavia, district heating systems have been dominant for decades. In many countries, regulations were written long before decentralized energy systems were possible. That creates barriers.
In some cases, building owners experience barriers when they try to feed electricity back into the grid. District heating legislation prioritizes the cheapest short-term solution, to protect consumers, rather than what is most sustainable long-term.
And construction can be a conservative industry. New approaches often require years of proof before gaining acceptance. But change is already happening.
As energy independence becomes a geopolitical priority and sustainability targets tighten, governments and utilities are beginning to reconsider how energy systems should work.
The future: decentralized energy networks
Looking ahead, our energy systems may become far more decentralized.
Instead of relying on a few massive power plants, we could see many smaller energy nodes across cities.
Buildings producing energy.
Buildings storing energy.
Buildings sharing energy with their neighbours.
Slowly connecting into local energy communities. This doesn’t replace the grid. It strengthens it.
A more distributed system creates resilience. If one energy source fails, others can compensate.
And importantly, it allows us to capture value from energy that currently disappears into thin air.
One of the most interesting points Nicolas made during the conversation was this:
Energy Machines hasn’t invented revolutionary new technology.
Heat pumps already exist.
Heat exchangers already exist.
Geothermal systems already exist.
The innovation lies in how the systems are organized.
Instead of treating buildings as isolated silos, the approach looks at how energy moves through an entire ecosystem.
Once you start thinking that way, opportunities appear everywhere.
A simple question for the industry
For an industry focused on sustainability, construction still wastes extraordinary amounts of energy. Not because we lack solutions.
But because we often fail to look at buildings as systems.
Or networks.
Or energy infrastructure.
If we begin treating buildings as energy machines, capable of producing, storing, and redistributing energy, the role of buildings in the energy transition changes dramatically.
And the next time you walk through a building full of mechanical systems quietly humming away, there’s a question worth asking:
What energy are we wasting today?