For the last two and a half months I’ve shared examples of good home design from around the world. In a nutshell, good design includes using natural energy flows to heat and cool a structure. Natural energy flows include sunlight for winter warmth and wind for summer cooling.

A common term used for this approach to building homes is ‘passive design’. This approach to housing allows a well designed home to ‘just sit there’ and achieve comfortable temperatures year round with low power bills.

From desert to mountain, and from the tropics to cool temperate regions, I have included seven styles of homes so far in this column. For the eighth example I am offering a twist, because who in their right mind would include a 100 year-old New Zealand villa as an example of good home design?

However, the process of transforming a cold, draughty villa into a cosy, warm home is only a matter of following the basic design principles from other high performance homes that we can see around the world. Just as a reminder, the basic design elements are these: solar gain, thermal mass, insulation, cross ventilation, and a centrally located fixed heating source.

The first challenge of turning a century-old villa into a passive solar home is increasing glazing to the north and decreasing glazing to the south. In other words, this means adding windows and/or glass doors to capture more winter sunlight and removing windows or glass doors that receive no direct winter sun.

This type of work is more than likely to require building consent, so make sure you do your homework. Special care must be taken to not compromise the bracing of the home or its weather tightness.

Any northerly facing window is likely to provide an ample supply of free winter heating as long as the sun is not blocked by trees or neighbouring buildings. Once you have checked on potential winter shading, decisions can be made on increasing the amount of north facing glazing.

At the same time, southerly facing windows simply lose heat from a home almost continually from May through August. Replacing some of these cold windows with insulated walls will hold more warmth within a home, but remember all work needs to comply with the building code.

Next week I’ll tackle the misunderstood issue of thermal mass.

Peace, Estwing