Energy and cost savings with continuous low temperature heating versus intermittent heating of an office building with district heating

Future low-temperature district heating systems (LTDH) require supply and return temperatures as low as 55 °C and 25 °C, respectively. In this direction, the use of night setbacks in heating of office buildings is a problem. This article investigated in a typical office building with large distribution system by tests and simulations the energy and cost savings by changing the control of the heating system from a continuous high-temperature operation either to a high-temperature intermittent heating or to a continuous lowtemperature operation. Both strategies secured thermal comfort and resulted in similar energy savings of approximately 11% in the specific building. The reduction of the return temperature was higher under continuous low-temperature operation, resulting in additional cost savings due to a motivation tariff for low-temperature operation used in Denmark. As a result continuous low-temperature operation can achieve the highest total cost reduction for heating of 23.1%. Even if the results refer to the specific building, continuous low-temperature heating may result in significant energy savings in other buildings with large distribution systems. Moreover, implementing motivation tariffs towards LTDH may provide additional economic incentives. Therefore, it is interesting to investigate continuous low-temperature heating in each building and quantify the cost and energy savings towards LTDH.