Building Retrofit and Energy Conservation/Efficiency Review: A Techno-Environ-Economic Assessment of Heat Pump System Retrofit in Housing Stock

Abstract

The world has not been able to achieve minimum greenhouse gas emissions in buildings’ energy consumptions because the energy and emissions optimization techniques have not been fully utilized. Thermal comfort is one of the most important issues for both residential and commercial buildings. Out of the 40% of global energy consumed by buildings, a large fraction is used to maintain their thermal comfort. In this study, a comprehensive review of the recent advancements in building energy conservation and efficiency application is presented based on existing high-quality research papers. Additionally, the retrofit of the heating/cooling and hot water system for an entire community in Cyprus is presented. This study aims to analyze the technical and environmental benefits of replacing existing electric heaters for hot water with heat pump water heating systems and the use of heat pump air conditioners for thermal comfort in place of the existing ordinary air conditioners for space heating and cooling. One administrative building, 86 apartments (including residential and commercial) buildings, and a restaurant building is retrofitted, and the feasibility of the project is determined based on three economic indicators, namely; simple payback period (SPP), internal rate of return (IRR), and net present value (NPV). The electrical energy required by the hot water systems and the heating/cooling system is reduced by 263,564 kWh/yr and 144,825 kWh/yr, respectively. Additionally, the retrofit project will reduce Cyprus’ CO2 emission by 121,592.8 kg yearly. The SPP, IRR, and NPV for the project show that the retrofit is economically feasible.

Does the Net Present Value as a Financial Metric Fit Investment in Green Energy Security?

“…This understanding of NPV is used in capital budgeting and investment planning, enabling analysis of a projected investment or project [11]. The application of NPV in capital budgeting and investments is widely presented in the literature, e.g., [7,[12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27]. The researchers emphasise the importance of NPV for investment planning.…”

“…The researchers emphasise the importance of NPV for investment planning. Net Present Value enables the comparison between the money that must be paid to complete the planned investment with all the cash flows that the undertaking will generate in the future [7,[12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27].…”

“…Many factors are influencing the preference for absolute metrics or relative metrics in practice. They may depend on the company's policy, bank requirements, and shareholders' requirements [7,[27][28][29][30][31][32]. We do not develop the topic of factors that influence decision-makers choice between absolute and relative metrics.…”

Experimental and Numerical Analyses of Thermal Storage Tile-Bricks for Efficient Thermal Management of Buildings

“…The building sector is the most energy-consuming sector globally, as it consumes 35% of the total power generated and emits CO 2 at everhigher levels, i.e.,~10 GT which is equivalent to one-third of the total emissions of the world. This means that the building sector is moving away from the Paris Agreement of maintaining the global mean temperature rise below 2 • C. One of the main reasons behind such alarming environmental threats is that fossil fuels are the main source of energy generation which cause pollution and global warming [2] and the conventional means of thermal regulation of building such as heaters, air conditioners and HVAC systems are contributing in the greenhouse effects [3]. Renewable energy, e.g., solar, wind, biomass and geothermal, etc.…”

Carbon Dioxide Footprint and Its Impacts: A Case of Academic Buildings

“…Across the world, the energy requirement is increasing rapidly due to the attraction of urbanization facilities and the human population [6][7][8]. The world's largest CO 2 contributors are buildings, as the current building structures are demolished and rebuilt as huge buildings like skyscrapers to accommodate the population in urban areas [9][10][11]. It is reported that the building sector is responsible for almost 40% of global CO 2 emissions.…”