Reducing Energy Consumption, while Protecting the Environment - Energy and Climate: How to Achieve a Successful Energy Transition - page 55

reaching 80 000 h and a layout enabling an optimal distribution of light in
buildings [43].
Energy conservation can be ensured by using better performing heating
devices such as high efficiency boilers (condensing boilers), heat pumps or
cogeneration.
Cogeneration and heat pumps enable a better use of electricity. In a
fossil fuel power plant, electricity is produced from a heat source with a
yield which, in most cases, does not exceed 35-40%. The remaining
energy is released and transmitted to the refrigeration air or water. In the
case of cogeneration, the heat released is used for heating residential
buildings or industrial installations.
A heat pump operates according to a different principle. It operates in a
way similar to a refrigeration device. By withdrawing heat from an
external medium (water or air), it supplies a quantity of heat much larger
than the electrical energy consumed. The ratio of the quantity of heat thus
delivered over the consumed electrical energy (coefficient of performance
or COP) is frequently around 3.
Cogeneration is mainly applied in industry and in the residential or
tertiary sector, while heat pumps can be used for individual houses.
In the residential area, a huge growth has occurred in terms of energy
consumption. In France, in the case of an old building, dating from a year
before 1975 (date of enforcement of the first thermal regulation), average
thermal losses are around 330 kWh/m 2 /year. The application of the recent
regulation RT 2005 should lead to losses limited to 85 kWh/m 2 /year.
By further improving the design of the building, it is possible to lower
the level of losses down to 15-20 kWh/m 2 /year, which corresponds to the
'passive' house concept. In such a case, it is possible to maintain the
required temperature in the house through natural solar input and the heat
produced as a result of human activities [44].
The next step (further reduction of losses and increase of external solar
input) leads to the concept of the able to export

energy. From the stage when heat losses do not exceed 50 kWh/m 2 /year,
energy provided by solar thermal or photovoltaic panels can compara-
tively easily exceed the heating needs of the building.
Further developments are needed to ensure a better integration in the
structure of the building of thermal solar panels supplying hot water and
heating and also photovoltaic panels producing electricity. The develop-
ment of the equipment which is nowavailable facilitates the integration of
solar panels into the building. It becomes possible to install solar roofs or
walls. Such concepts lead to the need to revise the architecture and even
the structure of residential heating.

positive energy building,