Modelling Waste Energy Recovery Systems: Application to Hotels

03/07/2025

In 2023, tourism was responsible for 15.8% of the Portuguese gross domestic product. The increase in hotel units and their occupancy obliges different stakeholders to adopt innovative solutions aligned with the goals of the European Green Deal for reducing CO2e emissions. This dissertation aims to evaluate energy recovery solutions, such as heat recovery in hotels' HVAC systems, and their contribution to increasing energy efficiency and achieving the nZEB criteria. This work is divided into four stages: 1) identification and categorisation of different energy recovery technologies, 2) evaluation of the implementation potential in different case studies, 3) modelling of heat recovery systems, and 4) assessment of the main factors affecting the efficiency of these technologies. Among the identified technologies, heat recovery presents the most significant potential for energy savings. In the modelled scenarios with heat recovery in air handling units, these systems reduced HVAC primary energy consumption by up to 18% compared to configurations without heat recovery. With the increase in the overall efficiency of equipment, distribution losses are becoming more critical, so the assessment of the efficiency of recovery systems focused on analysing thermal losses in HVAC and domestic hot water pipework in case studies. The study concluded that low levels of insulation can result in a loss of 20% of recovered energy. Despite the average consumption of the case studies being above 200 kWhPE/m2, the study concludes that heat recovery, even in temperate climates like Portugal, helps bring hotels' energy performance closer to nZEB levels, which, according to the literature, should be around 100 kWhPE/m2 with in-situ renewable energy production.

Authors in the community:

• 

  A

  António José Alves da Silva Santos

  ist188614

Supervisors of this institution:

• 

  C

  Carlos Augusto Santos Silva

  ist23960

• 

  A

  Armando Teófilo dos Santos Pinto

  ist62195

PhD in Sustainable Energy Systems

mechanical-engineering - Mechanical engineering

Keywords

• nZEB Hotel
• Energy recovery in buildings
• Heat recovery modelling
• Heat recovery systems efficiency in buildings
• Heat recovery optimisation.

eng - English

Instituto Superior Técnico

CC-BY - CC-BY

Financing entity

Fundação para a Ciência e a Tecnologia

Number for the project, award or grant: SFRH/BD/120719/2016