What is a Sustainable house?
A house that’s consumption of natural resources, observing its whole life cycle, is less than the natural resources of the given area, fallen on the house. (Medgyasszay, 2009)
The sustainable house uses the concepts of an environmentally friendly, passive and zero emission house, but respective to its definition, sets up two more important criteria:
- The sustainable house concept does not aim to minimize the energy consumption of the building, but to the cost-effective optimization dependent on geographical conditions.
- According to the geographical conditions and individual consumption the concept stipulates different regional requirements that will motivate a more equitable society.
The energetical criteria of the “Sustainable house” concept (version 1.0):
A “Sustainable house”, defined in Hungary, can only use the natural energy capital of the country in a renewable manner. According to this capacity and the current technical pontential of the country the building’s energy need can be covered by these resources:
- heating: biomass, geothermal sources (thermal water), solar;
- hot water: solar, biomass;
- cooling: electricity gained from renewable resources;
- cooking: biomass, electricity gained from renewable resources;
- lighting: electricity gained from renewable resources.
What does sustainable usage of renewable energy resources mean?
Heating – hot water production – cooking
The solar energy that arrives to this countries land is much more than the total energy needed (1800 PJ ). Its utilization could be free for individual or public purposes. The problems with solar energy utilization are the storage of the solar energy and the initial cost of the production/storage equipment. The theoretical biomass potential of Hungary for energetic utilization is 203-328 PJ, from which 200 PJ is accessible, according to the calculations of the Hungarian Academy of Science. According to other studies. [Giber, 2005] only 67 PJ is accessible. Currently, the majority of the utilized biomass in the country is used for industrial electricity production and the efficiency is questionable. Direct thermodynamic usage is advisable for the major part of biomass usage, this means at least 90 PJ could be gained for heating and hot water production. For larger scale usage, a further possibility is the utilization of our readily available thermal water. According to the Subcommittee of Technologies of Renewable Energetics in the Hungarian Academy of Science, out of the theoretical potential of 63 PJ, 10 PJ could be utilized. [Bohoczky, 2008]
In Hungary renewable resourcesthat can produce electrical energy are the following: solar, wind and biomass. The theoretical potentials of the first two are significant, but the really accessible energy is much less. Calculations without biomass resources are approx. 15-25 PJ per year.
What requirements a “sustainable house” has to comply with?
Hot water production can be covered by 60% solar energy and 40% biomass resources. Calculating with 10 million “standardized consumer” (this is the population of Hungary) it sums up in 10 PJ NET and 12.5 PJ GROSS energy consumption.
The energy demand of heating can be calculated two ways:
- According to the energy demand per square meters: the country’s total building stock is 480 million square meter. . Continuing with the above assumption it means maximum 90+10-12.5=88.5 PJ can be used for heating. With a supposed 85% efficiency of building machinery in Hungary the total energy consumption for heating of a sustainable house is not more than 43 kWh/m2/year.
- According to the energy potential per capita: dividing the potential (88.5 PJ) by the population (10 million) the result is 8.9 GJ, or 2,400 kWh/pers/year. This means approx. 5.8 q, or 1 m3 firewood per person per year. Considering, that this amount covers the heating of workplaces too, for the dwelling-house remains 4 q, or 0.7 m3/pers/year.
The cooling energy demandhas to be reduced radically in the case of residential buildings. In the case of self-contained houses, adequate architectural and structural design features can completely eliminate this demand.
In case of office and multi-storey buildings, instead of the conventional air conditioning, with the usage of heat exchanged airing, structure-cooling or geothermal heat-pumps, the energy demand of cooling can be significantly reduced.
The electrical energy demand of other devices (oven, lighting, washing machine, etc.) in a sustainable house defined in Hungary, cannot be more than 25 PJ / 10 million pers, which is 700 kWh/year, that means with a presumable 50-50% of domestic and communal consumption 350 kWh/pers/year as a limiting value.
- Medgyasszay Péter: Helyi műemlékvédelem alatt álló épület felújítása “fenntartható ház” koncepció mentén In Alaprajz Tervezői Napok Konferencia, konferencia előadás, Budapest, 2012. május 17.
- Medgyasszay Péter, Déri-Papp Éva: Megvalósítható-e az energetikai fenntarthatóság egy helyi védettségű épületnél? In CEP Clean Energy & Passive House EXPO, Műemlékvédelem alatt álló épületek energiahatékony felújításakonferencia, konferencia előadás, Budapest, 2011. október 20.
- Medgyasszay Péter: What means “Sustainable House” in Hungary? In Proceedings of the 16th “Building Services, Mechanical and Building Industry Days” International Conference pp.393-398
- Medgyasszay Péter: Célok és lehetőségek a fenntartható házak létesítésére In Energiagazdálkodás 2010/3 pp. 3-6
- Medgyasszay Péter: Sustainable house? Naturally! In DVD Proceedings of the Central Europe towards Sustainable Building 2010 International Conference
- Medgyasszay Péter: Fenntartható ház? Természetesen! In Régi-Új Magyar Építőművészet, Utóirat 2010/2
- Mennyit esznek a házak? Index, Zöld energia rovat, 2011. november 14
- Under identical climatic circumstances in regions with poorer economic power (usually less dopulous and richer of natural resources) less strict requirements have to be implemented, that means cheaper building systems can comply with them.
- The anual primer energy demand of Hungary is 1153.2 PJ [KSH, 2005]
- According to the calculations of the Hungarian Academy of Science the theoretical potential of photovoltaic utilization of solar energy is 1750 PJ/year, and 530 PJ/year in case of wind power.
- Calculating with 10 million inhabitant with a comsumption of 40 l/day of hot water. The energy need up to 60% can be covered by solar energy. The supposed efficiency of building machinery is 80%.
- Estimation: 4 million dwellings with an average 80 m2, times 1.5 considering the office and public buildings.
- 88.5 PJ * 0.85 = 75.23 PJ = 20 912 000 000 kWh; 20 912 000 000 kWh / 480 000 000 m2 = 43 kWh/m2
- Giber, 2005
- János Giber: (in Hungarian) The role of renewable energy resources in energy supply. Ministry of Economics and Transport, Budapest, 2005.
- Bohoczky, 2008
- The future of renewable energy resources in Hungary. Presentation, 2008.
- KSH, 2005
- Hungarian Central Statistical Office: Hungarian Statistical Yearbook 2005.