(MENAFN- Muscat Daily) Once the passive design strategies are applied, there is still a need to cool buildings with active means during the hot summer months. How can an Eco House provide a comfortable indoor climate without the usual energy-demanding air-conditioning systems?
Muscat experiences very hot and humid summer months, but the winter is quite pleasant. During the winter season an Eco House that has proper orientation, ventilation and insulation can provide a stable and comfortable indoor climate without having to activate any additional climate systems.
However, during the very hot summer when temperatures and humidity are rising beyond the human comfort zone, active building systems for cooling and dehumidification have to be added.
The good news is: If we add active systems to the passively performing house our energy savings are factorised. In other words, with a passive Eco House as a basis we need to add only a minimum of energy for comfort during the summer months.
Active systems do not replace but complement passive components.
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How then can an Eco House provide a friendly and healthy indoor climate in summer without the usual air-conditioning systems?
There is a better solution for cooling than an air-conditioning system that produces noise and draft. This system is called radiant cooling. Radiant cooling works much the same as floor heating, but in a reversed manner.
Cold water flows through small pipes, which are incorporated in the plaster of the ceilings or walls. Through a principle of energy exchange called radiance, the persons in the room experience pleasant cooling.
Thus, parts of the building are cooled and not the air, like in conventional air-conditioning systems. Using cold water instead of cold air is already saving a lot of energy, and transporting ‘cold' with water is several times more efficient. Thus, radiant cooling is a silent system providing maximum energy-efficiency and human comfort.
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Since in an Eco House there is no air-conditioning system and the building should not let in humid air in the hot summer months, what about fresh air?
A hygienic air exchange will provide an appropriate amount of fresh air per person from outside into the house. The exhaust air will change energy embedded in temperature and humidity with the incoming fresh air and thus maximise energy recovery.
The airflow and velocities are relatively low. Radiant cooling and hygienic air work very well together. In fact, they complement each other.
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How can an Eco House control the active systems?
In winter the Eco House will be operated ‘by hand', pretty much like houses in the old days. But when it comes to the hot summer period, a computerised Building Management System (BMS) takes over the control of the active systems.
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Can an Eco House produce its own energy?
An Eco House can save probably up to 70 per cent of total energy compared to a standard villa. These are substantial savings, but still we need to cover 30 per cent.
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How can we do this? Oman has a lot of sun. Why not make use of it and instal PV cells and a solar thermal panel on the roof?
In Germany for instance, thousands of roofs are already equipped with solar cells. This month, the combined power of the solar panels installed on private houses produced up to 22MW power, which is the equivalent of 20 nuclear plants. For an Eco House zero-energy
is a benchmark. Zero-energy means that at the end of the year, the house will produce as much energy as it will use. An even more radical concept would be a plus-energy-building, which stands for a building with a surplus on energy over the course of a year.
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Wouldn't it be great if each new Omani house could generate its own power and energy bills were history?
Energy is still relatively cheap in Oman because it is subsidised. If people have to pay for the real energy costs, the Eco House would be the only solution. Fossil resources are on the decline and therefore it makes a lot of sense for Oman to become a leader in energy saving and renewable energy for homes.
Nikolaus Knebel and Martin Werminghausen are both Associate Professors at the Department of Urban Planning and Architectural Design at the German University of Technology in Oman (GUtech) and lead the GUtech Eco House team, which will be built in partnership with Hoehler+Partner architecture and engineering consultants, Muscat.
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