Costs and benefits of preparing existing Danish buildings for low-temperature district heating

Abstract

This paper aims to provide an overview of the costs and benefits of preparing existing space heating systems for low-temperature district heating. Necessary heating system improvements were assessed based on previous work carried out on the topic. This included evaluating the necessity of installing larger heating elements and improving heating system control. The costs of the identified heating system improvements were then estimated and compared with the savings achieved if district heating temperatures were lowered, from the perspective of both the total Danish energy system and the individual district heating customers. The investigations resulted in simple payback times of 1.2-4.3 years from an energy system perspective and 0.3-18.7 years for an individual district heating customer. The current study thus indicates that it is economically feasible to invest in an improved heating system control to enable a reduction in the district heating return temperatures.

Method for Assessing Heat Loss in A District Heating Network with A Focus on the State of Insulation and Actual Demand for Useful Energy

“…The conditions are much more severe than those provided by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) Standard and the ASHRAE Climatic Design Conditions [41]. For instance, in the section of Annual Heating and Humidification Design Conditions, the ASHRAE Climatic Design Conditions [41] provides dry-bulb temperature corresponding to 99.0% annual cumulative frequency of occurrence (cold conditions) accounting for −29.9 • C. According to the design conditions in Denmark described by Østergaard and Svendsen [42], the outdoor design temperature there is only −12 • C, which leads to significantly more moderate operating conditions. Omsk's DH network is an old and extra worn-out network with 2nd generation technology, which includes large losses and a higher proportion of fossil fuels: coal, natural gas, and heavy oil.…”

Roadblocks to Low Temperature District Heating

“…For this reason, it is difficult to assess quantitively the steps necessary for 4/5GDHN compatible building stock; instead a qualitative approach can be adopted based on progress elsewhere. There have been many studies on the compatibility of LTDHN with current building stock [23,67,[70][71][72][73][74][75][76][77][78][79][80][81]. Several of these papers present an analysis of the existing radiator system [67,81].…”

Comparison of 4th and 5th generation district heating systems

“…Both LTDH and ATDH can be considered as a response from the sector to the general trend of building energy renovations, which are significantly reducing the space heating demand. The building energy renovation trend is further enabling existing buildings, with radiators installations, to operate with supply * Corresponding author: og@danfoss.com temperature below 60°C for vast majority of the year [3], [4]. Another trend is the greater application of floor heating system for fulfilling the space heating demand, which have a maximum supply temperature demand of 45°C, which has resulted in that the temperature requirements for DHW preparation determines the minimum supply temperature to the buildings.…”