From near zero energy to zero CO2 emission building


Summer 2017

At the start of this decade, carbon emissions and energy consumption increased faster, as was predicted by the Roman club in their expertise Beyond the limits in 1992. It is well known, that the buildings sector in the EU consumes more than 40 % of total energy use. This problem became a priority at the EU Commission with the adoption of the Directive 2012 / 27 / & Directive 2010 / 31 Energy Performance of Buildings and Energy Efficiency. At present, across most of the EU, the political will for such action to enhance energy efficiency in buildings, and integrating renewable energies appears to be diverse. The EU Directive proposes that after 2020 all new buildings must be (near) zero energy as well as near zero CO2 emission buildings on energy use (NZCO2EB).

Although there has been much recent focus on measures to reduce emissions from new buildings, the existing building stock remains largely untouched and many refurbishment projects miss opportunities to reduce emissions and deliver low CO2 buildings. Knowledge of how to build new excellent energy-efficient buildings, and how to refurbish existing buildings to achieve greater improvements in energy efficiency & CO2 reduction, is already in place. It often makes economic sense, like any innovation once volume is increased, costs will decrease. There are demonstrations of what is possible, but many barriers to widespread mainstream effective action remain. The Energy Roadmap 2050 is encouraging, but it is long-term strategy. Accelerated action is necessary before 2020, hence the need for policy adoption in the regions of ZEROCO2, which show what is possible.

There exist many new innovative concepts, such as passive house, net metering, smart grid etc. There are many innovative standards across the EU28, but for the purpose of this part of the project, ZEROCO2 is showing that codes are evolving. Adopting passive house or a similar quality as the standard for both new build and the refurbishment of existing buildings will bring many benefits, some of which are outlined in this paper. There are many policies and technologies which lead to the near zero CO2 and near zero energy buildings. This is shown in recent research which indicates that over 70 per cent of global energy use could be saved by practically achievable design. Partners form 8 member states within the project “ZEROCO2 Promotion of near zero CO2 emission buildings due to energy use”, have finished the overview of the national, regional as well as local policies in this field. The findings were gathered by the Regional Policy Reports and published in one document- Common study.

The overview of the Regional Policiy Reports underlines that the idea behind the reduction of energy coming from fossil sources often has, as its starting point, the increased production of energy from renewable sources. In essence it should also focus on the concept of reducing energy consumption, by working on the technical and system characteristics of the buildings, which account for about 40% of the gross final consumption of energy. As member states have different climates and RES availability, it is also reflected in their energy policies. In EU regions, where solar radiation is stronger and more consistent and where the seasonal temperatures are higher (e.g. Italy, France, Greece, Malta), the requirement is for active heating and cooling by optimising passive design. In EU region where the climate is harsher and where exposure to light and solar heat is reduced (e.g. Slovenia, Finland, Germany, Lithuania) it is preferable to use higher efficiency systems and equipment as well as biomass as a primary energy source.

Many demonstration sites show that near zero energy and CO2 buildings already exist. In one case of an existing public building, a rough analysis of the opportunities to achieve near zero energy has been produced. The building, built in 1975, with a prefabricated construction system of a net area of 365m2 has 10cm mineral wool thermal insulation with salonite façade panels and plaster. The wooden ceiling was covered with gypsum cardboard panels and 15 cm thermal insulation. The building has been energy renovated except for the heating system. Two possible scenarios have been developed to achieve near zero CO2 as a result of energy use: 1) biomass boiler and photovoltaics, 2) Heat pump and photovoltaics (see Table below).

Table: Evaluated scenarios toward near zero CO2 building

As shown on the table it is evident that the both scenarios lead toward zero CO2, but scenario 1 has higher operating costs because of the use of biomass meaning that, from the operating point of view, the scenario 2 is more suitable for implementation without considering investment costs.

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