Electrics: Ventilation and Built-in Vacuums

ABOVE: A built-in central vacuum is the perfect solution for those with dust allergies, as it completely removes the particles instead of recirculating, them, as with standard vacuums.

Ventilation

Good ventilation is seen as a key factor in determining indoor air quality. In low-energy homes – and in the future, all new homes will be low-energy homes – more heat is lost from air changes than through the walls, roof and floors. There is increasing emphasis on building a shell which is airtight in order to address this issue. And it makes sense to both manage the air quality inside the house and to minimise the heat loss from air changes.

The standard ventilation routine in new homes and extensions is to fit trickle vents into the heads of the windows and, in addition, to fit extract fans in any wet rooms — kitchens, bathrooms, utility rooms. But trickle vents are ugly and they can be very draughty too — many people don’t like them. Hence there is a lot of interest in more elegant solutions.

Chief amongst these for self-builders is to fit a whole-house mechanical ventilation with heat recovery system (MVHR). This pipes fresh air in from outside into the dry rooms and draws stale air from the wet rooms: in the process, the heat is transferred from the outgoing (warm) air into the incoming (cool) air. There are also systems available that heat the incoming air and which thus cross over from being purely ventilation systems to becoming heating systems in their own right. They are also used in well-insulated homes to distribute the heat around the house so that if, for instance, there is a stove in one room, the heat coming from it can be shared around the house as a whole.

There are other options. There are wholehouse systems based on either pumping air into the house (positive pressure) or drawing it out (negative pressure) but not both at the same time, as with MVHR. And there is a negative pressure system that works passively – that is without any electrical fan – known as passive stack ventilation.

ABOVE: Houses built of SIPs (structural insulated panels) are so airtight that whole-house mechanical ventilation is required. As a result, the houses are extremely well insulated and energy-efficient. Read more about this project.

Built-in Vacuums

Rather than having one noisy machine which circulates a lot of dust whilst working its way around the house, a built-in vacuum system places the machine in a remote location (typically the garage or utility room) and uses a head plugged into a series of sockets placed strategically around the house. The advantages are that, in operation, a central vacuum unit runs quietly (provided the unit is located away from the main living areas) and what gets sucked into the head stays within the system. Depending on the size of your house, you need between two and five inlet valves or sockets into which you plug the end of your tube. This action causes the motor to come on automatically and the dust is then drawn down the pipes into the unit. They are particularly popular with self-builders because the ducting has to be built into the walls, which makes it a natural choice for new builds.

Central vacuums share much in common with whole-house ventilation systems. The basic components are quite similar – a large fan, lots of ducting, several outlets placed around the house – and maybe because of this, many self-builders tend to fit both.

Further reading:

• Lighting
• Smart Homes

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