## 1 Introduction
There are also barriers to the technical installations themselves, e.g., more complex solutions being needed than foreseen, the temperature of the waste heat being lower than expected or expensive transmission pipes [15; 16; 17; 18]. Some barriers are linked to the interaction between the district heating company and the waste heat provider. It has been found that the quality of the heat (volatility of volume and temperature) is often perceived differently by the district heating company and the waste heat owner. The latter tends to claim that the heat is of premium quality, whilst the district heating provider will often disagree. Complexity is added by the existence of asymmetric information about the heat flow of each party involved in the collaboration [19]. Split incentives between project partners appears to be important when implementing waste heat recovery schemes [18]. Investment in waste heat recovery also competes with alternative uses of investment capital [20; 21; 22]. The risk that the heat source will terminate its core activity or move premises is often mentioned as a risk and therefore a barrier. In [23], the authors assessed the risk of Swedish industrial waste heat recovery for the period from 1974-2014. The analysis verified that terminated industrial activity is a risk factor and that, in combination with cases in which there was a substitution for another heat supply, approximately 6% of all annual heat recoveries were lost. Other risk factors that were identified include a lower than predicted annual heat recovery and the use of heat pumps. Systems for urban waste heat recovery often rely on the use of a heat pump, which creates a dependency on electricity, making volatility and trends in the price of electricity a key factor. An advantage of urban heat sources is that they are typically local to the network. For example, data centres, sewage water treatment plants, underground stations and service sector buildings are usually in urban areas. The volume of heat that can be recovered from urban heat sources is usually lower than the volume available from large industrial processes. However, the fact that the heat sources are local and small has its own advantages. First, there is an opportunity to make use of multiple local heat sources, reducing the reliance on a single source, and therefore increasing the resilience of large DHNs. Second, to harvest the local heat source, close customer dialogue is needed. This builds trust and long-term engagement, which can create a competitive advantage for district heating providers over other heat suppliers who depend increasingly on digital interaction with customers [24]. Third, and most importantly, urban waste heat sources are fossil free (although the electricity used to power a heat pump may come from a non-renewable source) and readily available. Urban waste heat recovery is challenging but the potential fossil free energy potential of 1.2 EJ/year is a great incentive to overcome those challenges. Much attention has been given to the technical side of urban waste heat recovery. This is a natural consequence of the need for validated technical solutions in a newly emerging area. However, other aspects regarding risk, contracts and business arrangements are equally important. In this paper, results are presented regarding the issues of barriers to investment, contractual arrangements and business models. The results come from research developed during the ongoing ReUseHeat project. Urban waste heat recovery suffers from issues of technical performance as well as challenges with efficient contracting and business modelling. This technical uncertainty is further aggravated by a lack of legislation and standardisation of urban waste heat recovery investments.