Lyttelton’s Warm Wall was launched today. It is the culmination of much hard work by many committed supporters of Project Port Lyttelton’s Energy Matters iniative. It is yet another example of Project Port Lyttelton taking a practical step towards building a sustainable community.

Architect Roger Buck proposed the warm wall as a means of reducing energy consumption and showcasing simple yet innovative energy-saving technology. A number of Lyttelton residents volunteered the use of their homes for the showcase installation. Of these, the home of Tom Jones and Helen Hobson, which is the living space within the Harbour Light, was considered to be most suitable. The warm wall was manufactured free-of-charge by Christchurch’s Brian Woods and fitted by home-owner Tom Jones.

Roger says a few words about the warm wall

Why a warm wall?

Warm walls are not new technology by any means. They have been used in a form similar to that shown above in the United States for many years to introduce heat to industrial buildings. Roger Buck was inspired to introduce the technology into the home of Yevrah Ornstein after reading an article in Build Magazine, the magazine of the Building Research Association NZ (www.branz.co.nz). Fortunately for Roger (and ultimately Helen and Tom), Yevrah embraced the idea and allowed Roger to design and build his first wall warm in Queenstown (see below). Yevrah was so impassioned by the reality of his own warm wall that he is now supplying warm walls in New Zealand, www.warmwall.co.nz.

Yevrah’s warm wall in Queenstown Close-up of warm wall perforations

How it works

The principal of the warm wall is simple. The wall is fabricated from dark-coloured, powder-coated, sheet steel. The dark-coloured surface of the warm wall absorbs energy from the sun and uses it to heat the air within the cavity of the warm wall. The warmed air rises by convection to a plenum chamber at the top of the warm wall, and from there it is ducted into the building. As the air rises within the cavity, fresh air is drawn in to replace it through small perforations in the surface of the wall. If the opening to the building is at the top of the warm wall, then no mechanical assistance is required to duct the air into the building. If it is desired to have the opening at the bottom or middle of the wall, then a low power fan will be required to draw the warm air down through a central duct within the warm wall and into the building. To remove the dependence of this solution on grid power, the fan could easily be power by a small photo-voltaic cell.

At its simplest, the air into the building is regulated by a manually controlled louvre at the top of the wall. If you want to go more high tech, then a fan and louvres can be thermostatically controlled based on the temperature of the air in the warm wall and in the building.

The wall will offer most benefit in spring and autumn, but benefit will be gained on any cold but sunny day. In the height of summer, the louvres are shut off to prevent hot air adding to the heat within the building.

Fresh Air

An added bonus of the warm wall technology is that you are not just heating and recycling existing air within the building, but actually warming fresh air and bringing it inside. This is particularly useful on those blue-sky winter days when you may be reluctant to open a window and risk losing precious warmth.

Which Wall?

For optimum benefit, the warm wall should be facing the sun in the middle of the day. Helen and Tom’s home was an ideal choice for the warm wall because it has a north-facing wall with only one window. A warm wall may benefit many houses were the windows are facing the view rather than the sun.

What Next?

Lyttelton’s Warm Wall is hopefully just the first of many practical demonstrations of energy-saving measures intended to capture the community’s interest and promote conversation about sustainable living. If you have an idea for the next energy saving showcase or want to get involved, then please contact us at contact@lyttelton.net.nz.