HOW TO REACH ENERGY CLASS A
- ENERGY SAVING BUILDINGS
- HOW TO REACH ENERGY CLASS A
How to reach energy class A
To better understand the performance of Robur gas absorption heat pumps, a comparative test has been carried out with the cooperation of the engineering office Taddei - Dami Prato on a residential building in which the energy performance variation has been calculated according to the design solutions and the system choices as well. The building represents a good starting point, since:
• external walls with 25 cm wide Poroton blocks and thermal insulation with fiberglass, 8 cm wide vapor barrier and 8 cm wide hollow bricks;
• roof and terrace insulation with 10 cm wide polystyrene panels and first floor insulation on all open areas with 5 cm wide polystyrene panels;
• wood windows with insulated glass and insulated box with shutter.
The heating system has been designed with the best technologies available on the market:
• condensing boiler;
• radiant floor system.
The result of energy classification according to the structural design and the system above mentioned, is an energy performance rating of 31,44 kWh/m2 per year thus achieving energy class B Klimahaus. As it was expected, a "well-done" building and a "well-done" installation may lead to a valuable energy class, but not to A energy class, that would catch the attention in the real estate market.
There are two ways to achieve the A energy class: the improvement of the construction or the installation of innovative heating systems, such as gas absorption heat pumps.
The only solution to improve the building, taking into account that the insulation complies with MD 311/06 for the year 2010, is the use of Gasbeton blocks against heat bridges or the adoption of building thermal envolopes.
Building thermal envelope
Since this solution is more widespread than Gasbeton blocks, taking into account the building above mentioned, external walls with building thermal envelope results in energy performance rating of 28.02 kWh/m2 per year thus leading to energy class A.
The objective of energy class A is then met, but at cost of greater expenses that can be estimated as follows:
• external walls area = 2.389 m2;
• increase in cost for building thermal envelope = 40 €/ m2;
• cost for building thermal envelope = 95.000 €.
Solution with Robur gas absoprtion heat pumps (GAHP)
The use of Robur gas absorption heat pumps with radiant floor heating system, allows to avoid the building thermal envelope and allows to achieve an energy performance rating of 20.84 kWh/m2 per year and the energy class A.
The use of gas absorption heat pumps with low temperature radiators also allows to achieve the energy class A, with energy performance rating of 22.76 kWh/m2 per year.
The cost required is estimated as follows:
• heating capacity required = 100 kW;
• gas absoprtion heat pumps cost = 25.000 €;
• savings compared to building thermal envelope = -70.000 €.
The results above mentioned represent an interesting scenario as far as renovation in existing buildings is concerned. The use of gas absorption heat pumps lead to significant advantages, improving the energy class of existing buildings. In this case, the energy class A is achievable reducing the investment in the construction, with interventions on the heating system only.
Actually, the objective of KlimaHaus energy class A for new buildings, or the improvement of energy class for existing buildings can be easily achieved with cost effective heating systems using renewable energy.
A further advantage of gas absorption heat pumps can be mentioned: with small increase in purchase costs, these devices can be supplied in reversible type to produce cold water even for summer cooling.