Renovating Building Groups in the Mediterranean Climate: Cost-Effectiveness of Renewable-Based Heating Alternatives in the Italian Context

Abstract

District level approaches for the renovation of the building stock boost the implementation of energy efficiency measures (EEMs), taking advantage of the economies of scale. International Energy Agency Annex 75 aims to assess the cost-effectiveness of renovation strategies at the district level, combining EEMs and renewable energy sources. For this goal, a building energy model is simulated with the Energy Plus dynamic calculation engine for assessing the generic district of the Italian case study, representing the residential stock from 1960 to 1980, placed in two prevailing space-heating dominated climates; then, a cost-effectiveness evaluation of each scenario is conducted to support stakeholders’ decision making. In particular, envelope insulation is cost-effective only in northern zones, while new decentralized thermal systems are not convenient in any case with current envelopes. Once the envelopes are insulated, decentralized low-temperature air-to-water heat pumps with PV can cover all of the buildings’ energy needs, even implying a small increase in annual costs. The switch to district net scenarios is cost-effective only if coupled with PV. A rise in energy prices brings PV-based strategies under a 10-year PBT, except for solar thermal DH in northern areas, as well as non-PV-based options such as low-temperature HPs or biomass-fuelled DH in warmer and colder zones, respectively.

Integrating Passive Energy Efficient Measures to the Building Envelope of a Multi-Apartment Building in Sweden: Analysis of Final Energy Savings and Cost Effectiveness

“…The energy balance simulation results demonstrated that replacing the existing windows yielded the highest final energy savings. This corroborates the findings of [14,17,22], who analyzed implementations of EEMs in multi-apartment buildings located in similar climate conditions as the studied building. This indicates the vital role of windows as the largest contributor to heat losses in buildings in winter and the potential for a broader implementation of this EEMs.…”

“…A major challenge in energy renovation projects is to achieve energy efficiency requirements cost effectively [12,13]. Different studies [14][15][16][17][18][19][20][21][22][23][24] have investigated the economic benefits of EEMs for existing buildings. Dodoo et al [17] found that adding insulation to the basement walls is the most cost-effective EEM for a multi-apartment building located in southern Sweden.…”

Strategies and Actions for Achieving Carbon Neutrality in Portuguese Residential Buildings by 2050

“…It is important to highlight that, for this case study, neither the order of results nor the magnitude of global costs and primary energy consumption changed for the two simulated climates. However, it is noteworthy that P01 (passive-only solutions) was not cost-effective for I1V2 (Lisbon) but approached the cost-effectiveness threshold for I2V1 (Porto), characterised by colder winters, where insulation is more critical to reduce thermal losses [42,43].…”