Determining the least-cost heat-saving strategy towards a natural gas-free built environment at neighbourhood level.

Abstract

The built environment is with its high share in the total energy consumption, with natural gas as main source, an important factor in achieving global and national climate goals. In the context of strategic heat planning towards a natural gas-free heat supply, both heat supply and -demand side need to be addressed to keep investment costs towards building-owners as low as possible. This thesis is aimed at determining the economical optimal balance between the two management approaches in order to identify the least-cost heat-saving strategy towards a natural gas-free built environment.

It proposes a methodology, based on a marginal cost-based method, to provide insight into the costs incurred for supplying-/saving heat that are directly related with the level of heat demand in order to decide whether it is beneficial to reduce or supply heat. The idea behind this concept is that one should harvest heat by utilising the least-cost options first until this option exceeds the other option in marginal costs. As long as the consumption-related marginal costs of reducing heat demand remain lower than the marginal supply costs, it will be economically attractive for building-owners to reduce the heat demand.

With the neighbourhood Tuindorp in the city of Utrecht as case-study, the study emphasises the relevance of taking into account the local geographical setting in determining the least-cost heat saving strategy, since it affects the types and amount of sustainable energy resources and the specific energy-related building characteristics to be addressed. Given the uncertainty regarding the future sustainable heat supply scenario by the target year 2030, this research aims to determine the least-cost heat saving strategy for different potential heat supply scenarios, including individual and (semi-)collective heat supply systems.

Regarding the heat saving strategies, the results has shown significant variations in heat saving potentials among the heat supply scenarios. With high marginal supply costs, it appears to be more interesting to opt for higher demand savings than with low marginal supply costs scenarios. Independent of the scenario to be taken, the total annual costs will decrease, despite the renovation costs incurred. Where it is now often recommended to obtain, for instance, energy label B prior to implementation of supply systems, this study has shown the advantage of even going for higher energy savings. Based on the marginal cost approach, it concludes that a significant high heat saving potential of more than 50%, compared to the present level of heat demand, will be economically profitable prior to integrating new natural gas-free heat supply systems.