# Economic and Environmental Impact of Energy Saving in Healthcare Buildings
## 3 Results
### Usage of Renewable Energies  
[PERSON] et al. (2013) studied the facilities of the Espoo Hospital (Finland), and they concluded that the most affordable renewable solutions were biogas energy, wood chip heating, and ground source heating. Biogas energy was the most affordable solution although it is only suitable for large-scale projects since the system is not yet commonly used and some risk of uncertainty must be added [34]. Solar electricity was the most expensive method and snow storage cooling needs to entail certain societal benefits for it to be cost-effective.  
The current biomass energy conversion technology ensures the efficient operation of the facilities [35]. In the combustion of biomass, CO\({}_{2}\) emissions are almost neutral provided it is part of the base that the plants retain a higher volume of CO\({}_{2}\) during their growth as compared with that released during combustion.  
Figure 4: Potential of energy saving derived from optimization of lighting system.  
The use of solar thermal energy for hot water generation allows a reduction of energy consumption and a decrease of greenhouse gas emissions. In smaller buildings, hot water demand is relatively low and, therefore, the current systems usually do not use central distribution networks [36], provided such demand is satisfied by the electric hot water heater, near the consumption points. Installation of solar collectors on roofs ensures a drastic reduction of energy consumption and is regarded as an efficient energy supply alternative. If larger buildings with higher associated energy consumption rates are accounted for, remarkable efficiency of solar thermal energy equipment has been reported [37].  
Power generated by a photovoltaic field is fed into the public grid, allowing the production of electricity from solar energy; it is a solution that can serve to considerably lower energy costs and contribute to the overall decrease in emissions [38].  
Use of low-temperature geothermal energy is based on the fact that the ground below a depth of 7-10 m is maintained at a stable temperature, about 17 \({}^{\circ}\)C, regardless of the time of year or weather conditions. This energy source allows increasing the performance of the air conditioning equipment and has been set as a renewable energy in Europe since 2009 [39].  
[PERSON] et al. (2006) analysed the different possibilities for providing heating, air conditioning and hot tap water to a Spanish hospital. They considered several cogeneration systems with diesel engines and gas turbines. They observed that the most important parameter is the electricity produced and concluded that the control strategy and the size of the facility have a strong influence on the energy system [40].  
In order to quantify the economic and environmental impact from energy saving by usage of renewable energies, a total of eight hospitals and 25 healthcare centres were analysed for a three-year period.  
Figure 5 represents the potential average energy saving per built surface (m\({}^{2}\)) area through the installation of renewable energy systems in healthcare buildings with less than 5000 m\({}^{2}\) (no beds) and hospitals larger than 5000 m\({}^{2}\) (with beds). A potential average saving between 2.5 kWh and 3 kWh per built surface area is observed, in a payback period lower than 10 years. Subsidies and grants can substantially reduce the time of the investment's amortization.  
The specific energy saving measures used were the following: replacement of heating boilers using fossil fuels, diesel or natural gas, with biomass boilers, use of solar thermal energy for DWH generation and installation of solar collectors on roofs ensures a drastic reduction of energy consumption.  
Figure 5: Potential of energy saving derived from usage of renewable energies.