Energy Savings in Passive Houses

Energy savings in passive houses are substantial.

The way that the a passive house is constructed minimises heat loss to such an extent that it is easily replenished by solar gain by product heat from electrical appliances and human occupancy.

The house can be traditional build or a passive precast solution.

The energy levels are about 90% less than a typical home.

Energy Savings are measurable in passive homes.


And with energy savings comes comfort for all the family.

In an average 110m2 house this will equate to savings between €1000 to €1500 per year. So a passive home is giving substantial savings over the lifetime of the house.

You may ask where the 10% energy is used. Well the bulk of it is for water heating and on certain days perhaps one or two a year some additional heating.

To understand the way heat performs in a passive house.

Let’s start by looking at the Passive standard

The building must not use more than15 kWh/m² per year in heating and cooling energy. Total energy consumption (energy for heating, hot water and electricity) must not be more than 42 kWh/m² per year

To get some idea of the actual requirements let’s look at the UK Ireland and the US

In the UK the passive house would use 77% less energy for space heating

In Ireland the passive house uses 84% less energy for space heating

And in the US the passive house uses between 75% to 85% less energy for space heating.

See also Passive standard house for actual examples


If a house has 100m2 in area then the energy requirements are as follows

1. Heating and cooling: 1500kWh per year

2. Total energy consumption 4200kWh per year

Space Heating with Passive houses

Space heating is treated differently in a passive home.

The white goods in the house produce heat which is used to heat the house.

The refrigeration the washing machine all emit heat as a by product of their use and it can be measured and accounted for in the passive design. The TV us the same as well as DVD etc.

The solar gain is of course included and finally the heat from humans and animals.

The average person emits 100watt each.

When this energy is added to the insulation and air tightness and the need for conventional heating is no longer required.

This is sometimes difficult for clients to get their head around.

Not having a heating system is a new phenomenon which needs getting used to.

To ensure that the house has a heat source a heat coil can be added to the mechanical heat recovery system. This would be used in the coldest weather. The use of such a heat coil would normally be for very short periods maybe a day or two.

The heat coil can be powered by a small heat pump or by solar photovoltaics or by utility energy.

A small stove can be used but it may overheat the room where it is located.

If the heating load is below 10w/m2 then the use of additional heating is not needed.

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