“The results of the heating system upgrades look promising. The investment costs are minimal and have potential for a lot of savings. Similar control systems are widely used in industrial processes, but the untapped potential in buildings is still huge,” says Harald Taxt Walnum, a research scientist at SINTEF.
SINTEF and the technical contractor GK collaborated to carry out the experiments, which resulted in significantly reduced energy consumption.
Taking electricity prices and weather forecasts into account
SINTEF and GK used MPC (Model Predictive Control) techniques in one of SINTEF’s own office buildings from the 1960s. The 60-year-old radiator control, which only regulated the heat according to the outdoor temperature, was upgraded with MPC, which is an advanced method for process control.
MPC uses a mathematical model of the system to predict future states and determine the optimal control actions to be taken. The model has been in use in the process industry in chemical plants and oil refineries since the 1980s. In recent years, it has also been widely studied for the control of energy systems in buildings.
The results show that over the course of one and a half months, energy consumption was reduced by 33 percent compared to expected consumption during normal operation.
Research scientist Harald Taxt Walnum at SINTEF.
“What distinguishes MPC from more traditional control methods is the ability to be forward thinking. Instead of just reacting to changes as they occur, MPC plans how the system will behave to achieve the best possible results over time,” says Walnum.
What distinguishes MPC from more traditional control methods is its ability to be forward thinking.
The system analyses multiple variables, including future electricity prices and weather forecasts, to use as little electricity as possible when prices are high. The heating adjustments were made more efficient when the system also received precise data on temperature and energy use in the building. This saved both energy and costs, and improved the indoor climate in the building.
“The effect would not necessarily have been as great if the study had been conducted at a different time of year, when fluctuations in temperature and electricity prices are smaller,” says Peder Ward, a civil engineer in cybernetics at GK.
We know that buildings account for about 30 percent of the world’s total energy consumption and almost as much of the energy-related CO₂ emissions.
The test period in April and May included several days where the temperature in the shade was relatively low, while the heat from the sun gave a completely different actual outdoor temperature.
Great savings potential
Many commercial buildings in Norway and Europe have old radiators. Upgrading to modern zone control, which requires new thermostats and sensors in each room, involves major investment costs. The MPC system uses existing infrastructure in the buildings, at a fraction of the cost.
Ward thus believes that this model could be an important contribution to the collective societal effort to improve energy efficiency.
“We know that buildings account for around 30 percent of the world’s total energy consumption and almost as much of the energy-related CO₂ emissions. In addition, most buildings that will still be in use in 2050 have already been built. If we expect to succeed in green transition, we have to look at how we can utilize existing buildings and technology more efficiently.”
Ward also believes that solutions such as MPC not only reduce energy costs, but also give buildings the flexibility to adapt to future needs.
“For example, the technology can be connected to smart networks where buildings help relieve the power grid by reducing consumption during periods of high energy load. This can also help support the use of renewable energy.
Some challenges remain
However, for the solution to be scalable, it requires more development.
One of the challenges in the project was to ensure stable data connections and to be able to handle periods of missing measurement data.
“The model handled this surprisingly well, but a backup solution is needed that can ensure continuous operation if data access or the MPC system becomes unstable,” says Ward.
Walnum is working on his PhD on the MPC system. He is looking more closely at how the system works over time, and how the model can work in buildings with more modern technology.
“We need to create a better “plug and play” solution that doesn’t require major local adaptations,” he says.
Energy-efficient collaboration
Ward and Walnum are nevertheless very satisfied with the results of the project. Their collaboration has resulted in a scientific article in the Elsevier journal, as well as real-world implementation of the new knowledge.
“This experiment is a good example of what we can achieve when research institutes and industry collaborate,” says Ward.
The study was conducted as part of the Research Centre on Zero Emission Neighbourhoods (FME ZEN).
Here is the link to the scientific article: Demonstration of a low-cost solution for implementing MPC in commercial buildings with legacy equipment
