PIV - Positive Input Ventilation

How does Positive Input Ventilation work?

A positive input ventilation unit gently supplies tempered, filtered air into a home using otherwise unused heat within a roof.

The benefits of this are enormous;

Firstly, it means that a significant
proportion of external pollutants
are prevented from entering the
home. Secondly, the use of the
otherwise unused heat in the roof
results in the ventilation unit
providing a significant net energy
gain to the home. Thirdly, there is
no better way to ventilate a home
than from the inside out via a single,
centrally located, supply air diffuser.

A good quality unit, fitted in your loft,
will operate at an almost imperceptible
noise level. You will hardly know its there. A properly designed and installed unit will ensure that old, contaminated, vapour laden air in your home is continuously diluted, displaced and replaced with good quality air. The result is improved indoor air quality and an environment in which condensation dampness cannot exist.

The old air exits through the thousands of air leakage points found in all homes. Indeed, positive input ventilation will even help to suppress unwanted infiltration (draughts).

The installation of a low energy positive input ventilation unit will ensure the air in your home is completely replaced with better quality air around 20 times a day. This is the recommended rate to maintain good air quality.

Your roof is an energy source. South east to south west facing tiles or slates absorb energy from the sun. Even the loft space itself is a substantial source of energy. During the heating season it will almost always be warmer than outside because of solar gain and conduction and convection losses from the home. Positive input ventilation units use the tiles/slates and/or the loft space itself to pre-warm the incoming air before delivering it into the home.

The input air enters your home at ceiling level, usually on your landing. This method re-circluates the warm air that rises and collects there as well as reducing the heat loss to your loft.

The slight pressurisation effect created helps reduce infiltration of unheated air through the leakage points found in all homes, having a consequential energy benefit.

In simple terms, a good quality low energy positive input ventilation unit will provide a significantly greater amount of energy into the home than the energy it consumes in the form of electricity, providing a considerable net energy gain.

Prices of the units, including supply and fit, range from £400-700. We can also supply a version of the product designed for ground floor flats, where there is no roof space.