Energy self-sufficent townhouses
“No power connection and no more expenses on oil and gas,” says Karl-Heinz maerzke, board member of HELMA Eigenheimbau AG, describing the aim of his latest project. By this he is referring to energy self-sufficient townhouses which, besides having the capacity to store thermal energy in a large water tank hidden inside, can also store electricity with batteries. This vision is now being realised in Berlin, too.
The first solar houses will be ready for occupancy as early as in 2012. They are located in the residential area of “Wohnen Am Landschaftspark” in Johannisthal where HELMA acquired the last available building plots and has already begun the construction of nine individual detached single-occupancy homes on plots up to a maximum size of just less than 600 square metres.
Approximately 160 square metres in size and each with 58 square metres of photovoltaic modules on their roofs, these homes will produce the remarkable output of 8,19 kilowatts-peak (kWp) – enough electricity to cover their own energy demand, electromobility included. To make this energy permanently available and independent of solar radiation, the charging and uncharging of the multicell accumulator is regulated by an intelligent control system which operates according to consumption. In this way, electric cars or bikes can be charged even during the night.
The sun also plays the lead role in heating – not only regarding the collector surface, but also, and mainly, due to a long-term solar storage tank with a total capacity of 9,300 litres. 65 percent of the annual heating demand is thus covered by solar heat. The rest is covered by district heating, 75 percent of which is produced on a renewable basis. The total energy demand of each of these classically masoned and well-insulated houses amounts to nine kilowatt-hours per square metre and year, falling below the requirements of the energy conservation regulations (EnEV) by 88 percent and below that of the passive house standard by 70 percent.
Despite these specified energy requirements, each house will maintain its individual character. “We are planning and building absolutely individually,” says HELMA’s Berlin representative Klaus Neumann. Guided by this philosophy, the company has built over 4,000 solid houses since 1980, “and none of them alike”. Nowadays, builders are even able to assemble their dream houses in 3-D technology. Furthermore, HELMA’s success is based on repeatedly being the first to make innovative solar and energy concepts ready for the market. In the case of this particular project, they are even the first in Europe. Klaus Neumann is convinced that saving energy instead of producing and feeding it into the grid is a particularly attractive concept which will fit in perfectly with the science location and its topical focus on solar energy.