MOTIVATION TARIFF – A KEY TOOL TO A LOW-TEMPERATURE DISTRICT HEATING NETWORK
By Tom Diget, Chief Operating Officer, Viborg District Heating Company
Viborg District Heating Company constantly works to improve the efficiency of the net- work. Lowering the temperature is essential, but the company needs the customers to cooperate – i.e., by lowering their return temperature. As an important tool for this goal, the district heating (DH) company has developed a motivation tariff, which gives some customers a discount, whereas others will have to pay more. The direct economic out- come of the tariff is a loss of approximately 270,000 EUR per year (income minus cost), but the efficiency gain in the whole network adds up to more than 679,000 EUR per year. This means a net benefit of around 400,000 EUR annually - a surplus converted into lower general heat costs.
Motivate the customer to lower the return temperature A DH company has many good reasons to lower the temper- ature in its network. Lower temperature gives a lot of different possibilities compared to a network with high temperatures. Not least, a lower temperature will help stay economically competitive against other heating technologies. The DH company controls the supply temperature and can re- duce it in times of lower heat consumption. But when the sup- ply temperature has reached a certain level, the return temper- ature limits how much further it is possible to lower the supply temperature. In Viborg, as in many other cities, the domestic hot water demand sets the minimum supply temperature in the DH network most of the year. In existing systems with old- er, more inefficient housing stock, there are limits to how low a supply temperature can be reached, typically around 60 de- grees, which is higher than the required temperature for heat- ing – most of the year. The consumer controls the return temperature. Therefore, the DH company has a clear interest in helping consumers low- er the return temperature. However, to a consumer, “low re- turn temperature” is, at best, of very little interest. Consumers want comfort, i.e., warm homes in the most simple, secure, and
cost-efficient way. Of course, the cost of heating must be low enough to be competitive against other options – but no one is interested in the return temperature. Thus, the consumer will act disloyally if another opportunity calls. So, to be able to low- er the temperature substantially, the DH company must find a way to motivate the consumers to lower the return tempera- ture even more. The benefits to the end costumers To motivate the consumers, they must understand what the benefits to them as consumers are. The list of benefits to the DH company includes lower heat loss, longer lifetime of pipes, more benefits from flue gas condensation, higher COP at heat pumps, and many more. But to most consumers, the real mo- tivation will always be saving money through lower heat costs. Some will be interested in other aspects (general benefits to society, climate change), and they should not be forgotten, but for most, the real motivation will be to save money.
Setting the goals for supply and return Supply temperature
The short-term goal for the supply temperature simply is a temperature high enough to supply a well-operated network. The long-term strategic goal should be to aim at the lowest
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