SUSTAINABILITY
Table 1. Carbon footprint of main primary energies [Source: ‘Energy – Carbon’ reference for new buildings]. Natural gas Fuel oil Propane Wood pellets Logs
kgCO2 eq/kWh 0.243 0.314 0.27 0.027
6% 1% 0%
2% 3% 7% 0.032 0.013 0 0
Plaquettes Photovoltaic Wind Solar French nuclear 0
0 n Nuclear 361 TWh
n Hydroelectricity 63 TWh
n Wind 37 TWh
n Photovoltaic 14 TWh
12% 69%
n Renewable heat and waste 10 TWh
n Gas 33 TWh
n Fuel oil 2 TWh
n Coal 4 TWh Figure 4. Electrical kWh produced in France. The implementation of energy
recovery systems in ventilation systems has also significantly reduced heating needs linked to fresh air. However, while greater use of air conditioning has been offset by greater use of sun protection, climate outlooks point to a considerable rise in cooling needs, whose impact can be appreciated with the ‘extreme’ weather files that include IPCC forecasts. The dynamic energy needs of a hospital building are complex to understand, as they largely depend on hosted services whose consumption profiles differ completely: according to the energy readings of a Brittany hospital delivered in the 2010s, heating and cooling consumption per m2
of a surgical
department are 8-10 times higher than the inpatient wards. However, those linked to DHW (domestic hot water) are 8-10 times lower (Fig 3). A simple approach based on the
proportion of the built surface area – not taking into account the consumption differences between departments – would not be appropriate at all to correctly estimate the energy consumption profiles of a future hospital building. So we need to have monthly energy readings for actual buildings, broken down by major entity and associated with characteristic quantities that can be used as distribution criteria: for example, the energy consumption of an intensive care unit according to the number of beds, a surgical department according to the number of operating rooms, or an imaging department according to the number of MRIs/Scanners. It is also essential to
IFHE DIGEST 2024
identify the main technical or programme decisions with an influence on consumption (air conditioning for accommodation and consulting rooms, ventilation type, specific equipment). By combining this data with outdoor
weather conditions and building performance, reliable consumption profiles can be created for future hospital buildings.
Recovery of waste and renewable energies Alongside developing need profiles, it is crucial to determine the potential combination of heating and cooling needs to recover waste energy. Indeed, in a hospital building, there are various pieces of equipment and departments requiring
cooling all year round, including electrical and IT rooms, MRIs, sterilisation autoclaves, kitchens, mortuary cabinets, and so on. Rather than releasing this available energy into the environment, it is preferable to recover it to pre-heat domestic hot water or a low-temperature heating circuit. An analysis of the region’s renewable
energy potential is also carried out and compared against needs to determine potential correlations between renewable energy sources and usage profiles: thermal solar energy covering some summer DHW needs or a short supply chain of wood chips.
Carbon assessment of energy sources With building energy needs known and controlled, the focus shifts to optimising the choice of energy supply and associated production. The carbon footprint of a billed energy supply (final energy) includes all supply chain energies to obtain primary energy, so an Urban Heating Network (UHN), whether supplied by a coal-fired station or geothermal energy, will not have the same carbon footprint. Currently, the carbon footprints of primary energies in France are as in Table 1. These primary energies can be
available at the point of consumption, and thus can also be final energies. However, the carbon footprint of electricity and heating or cooling networks depends on the ‘energy mix’ used to produce them. To be produced, electricity needs one
or several sources of primary energy, which is transformed and transported to points of consumption. Thus, a gas-fired thermal power plant transforms primary
Table 2. Carbon footprint of electricity depending on usage Electric
heating kgCO2 eq/kWh 0.21 0.066 0.066
Air-conditioning Domestic hot water
Lighting 0.066
Table 3. Morbihan network performance as per decree of 15 September 2006. Network
56 Réseau de Lanester
56 Réseau de chaleur Zac Centre 56 Réseau de Gumenen 56 Réseau de chaleur Liger
Company Lanester
C
Hennebont C Aurey
Locminé
56 Réseau de la Commune de Guer Guer 56 Réseau de Serent
Serent
C C C C
kWh
0.058 0.000 0.176
0.000 0.058 0.058
19
Source: RTE
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