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Thursday, 2014-04-17
Introduction to ecological heating and ventilation

This section presents various systems, which may be used for the heating and ventilation of an ecological house. Some systems can be used successfully in regular older houses as well; in particular the systems for “green” domestic water heating and ventilation, which could be installed in virtually any older building. We distinguish between space heating, i.e. heating of the rooms in the house, and tap-water heating, i.e. domestic hot water. (Solar collectors should heat the tap water in any house).

All houses need ventilation. In a super-insulated passive house, a ventilation system with heatrecovery is nessesary, as well as some means of heating tap water. We consider good ventilation essential in any type of house, however, it is difficult to achieve good energy performance without some form of reduction of the ventilation heat losses. This is why we recommend a minimum of three systems in any type of house:

  • Ventilation with heat-recovery
  • Space-heating
  • Tap-water heating

Reduce the heat losses first. Please keep in mind that the amount of energy needed should be reduced as far as possible in the construction of the house. Secondly, the location and orientation of the house and the amount of hot-water usage will dictate which system to choose. The initial investment cost, the life-length and the complexity of the system must be considered both for economical reasons but also for ecological reasons.

KISS (keep it simple). Ideally the inhabitants of the house should be able to understand and maintain the system - otherwise it might not work at all - and that would not be very ecological!

Air-air heat pumps. For some strange reason these economical heat pumps are practically unheard of in Ireland and Britain. They give off 3-5 times the amount of energy used and they are cheap and quick to install. One drawback is that they only heat a local area, much the same as a stove. Works best with open plan.

Geothermal heatpumps. We are not covering the large type of heat-pump that connects to pipes in the ground. The electrical power consumption of such a geothermal heatpump is usually 2-3kW with an output of 6-12kW. We consider that to be oversized for most low-energy and all passive houses.

Wood pellets and wood chips. On these pages we are not covering this type of environmentally sound source of heat. The reason is that there is an abundance of information about wood-pellets, wood-chips and pellet-boilers from many other sources.

We believe that the most ecological and possibly THE ONLY SUSTAINABLE SOURCES of heat for a house now and in the future are sun and bio-fuel. Solar collectors for heating the tap-water and wood- pellets or other bio-fuel for space heating. (except for passive houses that need practically no space-heating at all!)

Examples of combination of systems

1) Ventilation heat-recovery system & solar-collectors.
In a balanced ventilation system the old air is extracted from the “dirty“ rooms - kitchen, bath and laundry, and fresh pre-heated air is distributed through a duct system to all “clean” rooms. A small built in electric heater provides additional heat to the fresh air if required.
a) This system can be combined with other methods for space-heating and tapwater-heating such as Solar-panels, solid fuel stove, electric floor-heating, or any other system.
b) It is recommended for passive houses that need practically no space heating. It should be combined with solar-collectors for heating of the tap water.
c) It can be used in any house provided it is possible to install ducts to all parts of the house. Keep in mind that this is a ventilation system - there must be some heat to recover in the house for the system.

3) Micro heatpump running on exhaust air from house & stove.

  • The unit extracts stale warm air through a simple duct system from bath, kitchen and laundry.
  • The heat in the old air is amplified in the heat pump to heat the tap water.
  • The fresh air supply comes in through ventilation-slots in the windows of every other room in the house.
  • The space heating is provided by a solid fuel stove.
  • If the house is small and well insulated and small amount of hot tap water are acceptable; the micro heat-pump can be used for floor heating pipes as well.

a) For older houses with no ventilation system and need for plenty of hot water. Eliminates the need to run the oil heating in the summer months for hot water.
b) Simple installation with a minimum of ducts. The space heating is dealt with separately.

2) Ventilation heat-recovery system & micro heat pump.

  • This combination provides the comfort of a balanced ventilation system serving all rooms and large amounts of hot tap water.
  • The small heat pump replaces the regular electric water-heating tank. It produces hot water with a fraction of the energy needed.
  • It takes air from the exhaust side of the ventilation-heat-recovery unit.
  • Additional space heating can be provided through a solid fuel stove and if needed electric floor heating cables.

4) Air-air heatpump & solar collectors for water.
The quick fix solution in many situations - cheap to install and to run.

A simple air-air heatpump is heating the air in a central all or in a large open area in the house. The warm air spreads around the house if the doors are left open.

This type of heatpump combined with solar collectors for the production of hot tap water can provide an energy efficient system in a house with open plan. Please keep in mind that an air-air heatpump is not providing any ventilation of the house. You still need either holes in the walls (passive ventilation) or a ventilation system with heat recovery.



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