The office

Refitting buildings

Refitting buildings so that they are no longer reliant on fossil fuels, in this case gas, sounds good for the environment, but there is one major drawback. The extra demand placed on the electricity grid can overburden the system.

In refitting a listed office building, Johan Koekkoek solved this problem with a fully integrated system that combines heat pump techniques, batteries, fan coils and heat recovery units that can heat and cool different parts of the building at the same time.

What is the plan?

To do this he is employing a special heat pump technique that works with both the air and the ground (heat pumps normally work with either one or the other, but not both). Some of the energy is drawn from the ground through foundation piles fitted with heat exchangers. The rest is drawn from the air using the dry-cooler principle.

Normally you cannot cool a building all the time using a ground-source heat pump because when the ground heats up it cannot provide cooling. But here the heat pump can always provide cooling, which is vital because offices in some cases require more cooling than heating. A complicating factor here was the north-south orientation of the building. South-facing spaces generally need cooling while the north-facing spaces almost always require heating. Because the heat pump can exchange energy, it can cool and heat different parts of the building at the same time.

What can we expect?

As a result, the connection capacity of the electricity drops. That is vital in urban areas, where we see the increasing problem of providing electricity without congesting the network. The technique applied here makes that less of an issue.

That is because 16 batteries installed in the basement communicate constantly with the heat pump. The system software analyses the behaviour of the building for a period of two weeks with the help of AI. It examines energy demand and the price of energy determined by the dynamic energy contract, where prices are set a day in advance. On that basis, the software determines when it is financially and for grid load advantageous to charge the batteries.

Another advantage is that once the batteries are fully charged and there is a peak demand, energy is taken from the batteries and not from the grid. That’s called ‘peak shaving’. And naturally, if the price of energy is negative, the batteries will charge from the network. Another advantage of the battery system is that you always have a back-up. In the event of a power outage, you still have electricity for some time.

Innovations in energy

The effects of this integrated system are manifold: cheap tariffs, high yields and no burden on the grid. If fact, the energy taken from the network is reduced by about half. Moreover, the storage capacity of the batteries means that all peaks and troughs are levelled. Such a smart system in a historical structure is a unique achievement.

In terms of energy release, the refit makes use of fan-coil units for radiators. They offer low- temperature heating and can also provide cooling when needed. That means that no bulky radiators are needed but slender ones that can be discreetly positioned wherever the interior designer wants (e.g. storage units, beneath windows, inside ceilings). Ventilation is solved with a heat recovery system (balanced ventilation system) that pumps fresh air in, and extracts used air from which the heat is then removed before it is reintroduced into the building.

The great thing about this system is the way the elements communicate with one another to ensure the comfort of building occupants, to guarantee first of all high efficiency resulting in the lowest possible energy price, and to avoid overburdening the power grid.