Energy, economic and environmental analysis of waste heat recovery from a data centre for district heating

Abstract

This thesis evaluates the energy, economic, and environmental viability of reusing waste heat from the UPC Campus Nord data centre to meet the heating demands of the nearby Aularis buildings. Two waste heat recovery strategies are analysed: direct heat recovery (DHR), which uses a heat pump without storage, and waste heat recovery with thermal storage using a hot water tank (WT), to decouple heat generation from demand. The study begins with a detailed analysis of the operational profiles of both the data centre and the Aularis buildings, including their respective hourly thermal loads. An air-to-water heat pump using CO₂ as the refrigerant is selected to raise the recovered heat to useful heating temperature levels. Hourly energy balances are carried out to assess the potential for heat reuse, the performance of the heat pump, and the cooling savings in the data centre. Key performance indicators are defined to compare the two strategies in terms of energy efficiency, reuse factor, and demand coverage. The WT strategy shows superior performance in most metrics, achieving higher heat reuse, lower electricity consumption by the heat pump, and greater cooling energy savings. Economically, both strategies show favourable payback periods considering the useful life of the used equipment: 12 years for WT and 14 years for DHR. From an environmental perspective, both offset their CO₂-related investment emissions in under 1.5 years, with WT offering slightly greater long-term savings. The results confirm that recovering residual heat from data centres is a technically and environmentally viable solution for campus-scale decarbonization. Given its higher efficiency and better environmental and economic performance, the WT strategy is recommended as the preferred implementation model.