Which renewable energy source is right for your building?



3E designed a tool to assess the techno-economic feasibility of renewables in buildings

Since May 2015, the EPB regulation requires to study the feasibility of a range of renewable energy systems for any new building erected in the Walloon region, irrespective of its floor surface. Any building permit must include a feasibility study, assessing techno-economic and environmental impact of renewable energy generation, compared to a reference case.

Early 2015, 3E designed a first version of a software tool allowing EPB advisors to assess techno-economic feasibility of renewables in new buildings of less than 1000 m² of floor space built in Wallonia (hereafter called “EF-tool” – EF stands for “Etude de Faisabilité”, feasibility study in French).

Renewable energy sources and technologies currently taken into account are solar thermal systems for sanitary hot water production, heat pumps (air-air; air-water and ground-water heat pumps with and horizontal heat exchanger), PV systems, pellet boilers/stoves and cogeneration.

The tool combines key data extracted from the EPB software, such as building surface, heating needs, heating system output … with data entered by the user (e.g. roof surface, orientation, heating fuel, available space for an extra storage, …) to size the renewable energy system and to estimate the amount of green heat and/or electricity generated.

Figure 1: Primary energy consumption of renewable systems for a 156 m² new house heated by a gas condensing boiler.

For each of the different technologies, 3E’s EF-tool calculates its optimal sizing and installed capacity, as well as its primary energy consumption (figure 1) and CO2 emission (figure 2) compared to the reference system used in the EPB file.

Figure 2: CO2 emissions associated to each technology for for a 156 m² new house heated by a gas condensing boiler.

The tool also estimates the amount of renewable electricity or heat generated, as well as the additional investment or extra cost required by each technology. Finally, the EF-tool gives the internal rate of return (IRR) and the simple payback time of each renewable investment.

Results and assumptions are summarized in an automatically generated prefeasibility report, comparing between potentially interesting renewable technologies.

The new version of the EF-tool software is available since February 2017. This 2.0 version has some advanced new features such as a calculation engine for hybrid technologies (solar thermal & PV; solar thermal and heat pump; solar thermal & biomass boiler; PV & heat pump, PV & biomass) and a function to automatically fill out the feasibility study form required in the EPB software.

To date, 85% of EPB advisors are using this EF-tool to assess the feasibility of renewable energy systems in new residential buildings in Wallonia.