This section presents various systems, which may be used for the heating and ventilation of a 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 necessary, 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
- 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!
For new Scandinavian Homes passive houses we recommend one of two solutions.
We consider them equal and similar in cost of installation.
A simple wood burning stove combined with PV-solar panels. The most common arrangement for Scandinavian Homes customers as of lately.
Plus: Gives independence if you have access to small amounts of firewood, very trouble free long-life PV panels, completely free electricity when the sun shines in the spring, summer and autumn.
Minus: Work to collect firewood and cleaning, ESB still does not pay for the surplus electricity generated in spring, summer and autumn, have to buy electricity in winter for domestic hot water heating.
The stove handles the space heating with help of the ventilation system that moves the warm air around the house. Keep in mind that a passive house needs very little heat!
PV panels (electricity generating photo-voltiac panels) on the roof produce 230V electricity that is used to heat water in a water tank in the utility room and electric floor heat in the wet rooms. (ie bathrooms and utility room). When the sun shines there might be enough for other electric devices as well.
Air-water heat pumps. This is a good alternative to stove+solarpanels. This replaces both stove and solar panels. PEX water pipes are installed in the floors both downstairs and upstairs to handle space heating. The HP has a built-in tank in the utility room that handles all hot water requirements.
Plus: Very economical to run, completely automatic, very convenient, one system only.
Minus: The main unit will eventually wear out and need replacement after approximately 15 years, dependent on mains electricity, the exterior unit is ugly and a bit noisy.
Air-air heat pumps. Very economical to buy and to operate. 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. Great to improve an old house, especially if the layout is open-plan.
Geothermal heat pumps. This type of HP collects low-temperature heat via pipes in the ground. The heat is used for floor-heat and hot tap water. 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. Keep in mind that these little furnaces need cleaning and maintenance! And the pellets MUST be dry to secure a reliable function of the burner.
We believe that the most ecological and the most 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. PV-solar for electric generation to heat water and some space-heat. But heat pumps in their various forms are really efficient, cheap to run and very convenient. They work well in the winter compared to solar, so that is certainly a good option too. But it is always best to focus on REDUCING the energy needed, passive house, rather than to install a lot of complicated systems.