Diagram Architects

Rule 8 - Every house needs some of these…

I’ve just spent a good part of this morning on the site of one of our alteration-and-addition projects, very close to completion.

The insulation is concealed within the walls, ceiling and floor. The double glazed windows are installed, with frames painted and awaiting a final clean. The low-wattage fluorescent downlights need some final adjustments, but on the whole, the project is tantalisingly close to its final stages.

So it would be really easy to overlook one of the most important energy-efficiency aspects of the whole project – something that, if missed, could compromise all of the other smart technologies and fittings that are installed and ready. Something small, subtle and hard to notice:

The performing seals.

There’s no pool, balancing ball or buckets of fish in this project, but there will be seals everywhere. Seals on the door jambs, head and sill. Seals on the window sashes. The walls are sealed with taped and overlapped wall wrap, and gaps in the existing floors or junctions in material have been sealed with filler.

Air leakage in (infiltration) or out (exfiltration) of buildings is a major source of unwanted heat gain or loss. It is estimated that up to 25% of heating cost in older houses could be saved by limiting air leakage in simple ways.

Typical sources of heat loss include:

• Fixed wall vents (required by regulation in houses built before 1984).

• Poorly fitting windows and doors (increase energy cost by up to 15%).

• Gaps between external doors and windows and door frames, and around construction joints and pipes.

• Open fire places (five or more air changes per hour increase energy requirements by up to 120%).

• Vented skylights which allow warm air near the ceiling to escape.

• Non-sealable exhaust fans.

• Unsealed duct outlets.

• Downlights or recessed light fittings which require fixed ventilation to cool the luminaire (adding up to 10% to heating costs).

Source: Energy Smart Housing Manual, Sustainability Victoria

The gap around a poorly-fitting door can be equivalent to having a brick-sized opening in your wall, letting uncomfortably cold or hot air in, every hour of every day.

A good architect or designer should have a fair idea of where the possible paths of air leakage will be in your home, and what strategies to take to deal with them – make sure to ask. But dealing with infiltration and exfiltration is something you can do relatively easily with an existing house – even if you’re renting. Many of the solutions are simple and cheap, and some can be taken from house to house if required.

Windows and doors can be stripped with self-adhesive foams. Draught excluders - from the most complex self-operable seal to the basic bean-filled door snake – can be fitted to the base of doors. Silicon or acrylic fillers can be squirted into most gaps (but please check if the gap is doing something useful first). Self closing ‘top-hats’ can be fitted to some extractor fans, and diffusers to some skylights.

The best part of these very simple modifications is how immediate and noticeable the improvement usually is. It will take a lower setting on a heater to achieve the same level of comfort in winter, and an air conditioner would have to work much less in summer to achieve equivalent or better cooling

Australia is a long way behind the eight-ball when it comes to sealing buildings against air leakage. In parts of Europe and the USA houses are tested for air-tightness before completion with powerful air blowers, and fresh air enters the building through heat exchangers to limit the escape of useful warmth in winter. Our moderate climate and cheap energy has made us complacent, so even our new houses are often very poorly sealed.

It’s a terrible waste, because the solutions are so simple and affordable, and the benefits so marked. Couldn’t your house do with a pet seal or two?

brilliant seal photo posted on Flickr by mikebaird

This entry was posted on Tuesday, May 12th, 2009 at 4:41 pm and is filed under 10 rules for energy efficient house design, energy efficiency, green house design. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.