Construction is the single largest activity and industrial employer in Europe. In addition, the greatest energy saving potential lies in buildings. However, sustainability in the building sector must be assessed over the whole life cycle for all building components and materials. Housing has been identified as one of the three areas of consumption (together with food and drink, and private transportation) that are responsible for 70-80% of the whole life-cycle impact of products. In Mediterranean regions, solar radiation in summer can cause overheating of the building envelope (roof and walls) and the indoor environment, entailing the need for air-conditioning. Passive systems to limit solar effects mainly consist of ventilated facades and roofs, as they are most exposed to solar radiation. Vented roofs can greatly reduce heat due to solar radiation, but their performance is highly dependent on roof exposure and, more importantly, their perpendicular position to the wind. The benefit of so-called above sheathing ventilation (ASV) significantly decreases when the wind direction shifts from perpendicular to parallel to the eaves line. ASV positively affects thermal insulation thanks to convective heat transfer. Buoyancy-driven ventilation becomes irrelevant even with a very weak wind, while the air permeability of tiles determines an increase in performance. Thus, roof tile vents could be considered the best solution for passive thermal insulation for buildings in hot and mild climates.
The LIFE HEROTILE project aimed to design and produce two types of roof tiles (Marseillaiese and Portuguese roof tiles, which cover more than 60% of pitched roofs in Europe) with a shape characterised by higher air permeability through the overlap of the tiles and improved energy performance through under-tile ventilation. An air inlet will greatly increase the inflow of air and therefore the heat disposal. In addition, the tile design will be independent of wind direction, since the inlet and outlet channels will let the air flow horizontally as well as top to bottom. The project planned to test the tiles on real-scale buildings with Marseillaise and Portuguese roof types, located in different Mediterranean regions. The projects ultimate aim was to demonstrate that the designed tiles can help save up to 50% of the energy for cooling buildings. According to these estimates, the technology if widely adopted in the Mediterranean countries could generate savings between 5 000 and 13 000 GWh of electricity per year, avoiding emissions of 1.5-3 million equivalent tons of CO2.
LIFE HEROTILE successfully developed innovative roof tiles that can passively remove heat, so reducing energy consumption for the cooling of buildings by up to 50%. The tiles were introduced into the market soon after the project ended.
The project beneficiaries developed two new clay roof tile designs and demonstrated their improved performances in terms of energy consumption for summer cooling and greenhouse gas (GHG) emissions. Performance was evaluated under controlled conditions, and in real-world conditions by refurbishing the roofs of two demonstrative buildings in Cadelbosco (Italy) and Zaragosa (Spain). Moreover, the project team developed a software tool (SENSAPIRO) for the assessment of the cooling performances of roofs based on the results of the project demonstrations.
Specifically, the beneficiaries optimised the design of both Marseillaise and Portuguese roof tile types, and constructed test rigs and mock-ups of buildings for testing the roof tiles in controlled environment and semi-industrial scales. The tiles performed well in wind tunnel tests simulating rain and different wind conditions within the test rigs. An intensive monitoring campaign was conducted in the mock-up buildings, using a system with numerous sensors. The project team then conducted an analysis of the environmental benefits of the roof tiles. The main environmental benefits were a reduction of about 10-50% in energy consumption for house cooling during the summer due to improved passive ventilation of the roof envelope, depending on the type of roof, and a related reduction (10-50%) in GHG emissions and air pollution. Other benefits were reduced heating requirements in winter due to increased insulation (thicker air cushion) in the under-roof space, and reduced moisture in the above-roof space.
Considering the environmental benefits achieved, the project contributes to several EU policy areas, particularly the Clean Air Policy Package, Energy Efficiency Directive, and Energy Performance of Buildings Directive. The projects solutions can help achieve targets set for nearly zero-energy buildings, and for accelerating the cost-effective renovation of existing buildings with new provisions for smart technologies and technical building systems.
In the next 10 -15 years, 80% of pre-1960s roofs and 50% of pre-1990s roofs may need to be replaced, representing about 5 billion square meters of roofs to be restored. From the evaluation of the new tiles, energy consumption for summer cooling was reduced by about 10-30% for clay pitched roofs, but up to 30-50% compared with pitched metal roofs and up to 50-80% compared to flat concrete roofs. Extrapolating the analysis to 1 000 buildings expected to be refurbished with the new tiles in the next 5 years, about 5 000 MWh and almost 900 tons of CO2 eq. GHG emissions could be avoided. Therefore, the new tile designs could help the EU construction sector (refurbishment and new constructions) to achieve targets for energy efficiency and reductions in GHG emissions reductions, while facilitating the global market uptake of an eco-innovative EU product.
The main socio-economic benefits from the project relate to reductions in energy costs for house cooling and improved house comfort during the summer, the commercialisation of the new tiles, and the creation of new jobs (up to 30 in the long-term for the companies involved in the project).
Further information on the project can be found in the project's layman report and After-LIFE Communication Plan (see "Read more" section).