HOW TO DESIGN a smart house using the 15-15 rule

The most economical way to create a smarter home is to make two simple changes during the design phase, says Nelson Lebo.

“Homes right now are being built too big and with too much glazing. They’re expensive to build and expensive to heat. I start with something super simple, the 15-15 rule.” 1Make your home 15 per cent smaller A good architect can do this, and you won’t notice, says Nelson. Warren Clarke agrees.

“The number of people I talk to who say, ‘I need a separate laundry’. I ask how often they do laundry and they say, ‘only on Saturday’.

“But they want to dedicate a room, 10m², to an occupation that happens once a week. Our laundry is in a cupboard in the hall.”

In 2016, the average expected cost to build a home was $1906 per square metre. However, Statistics NZ notes that figure came from building consent information; it calculated the actual cost to be at least 10 per cent higher, around $2100 per square metre.

Shave 15 per cent off the floorplan of the average 182m² house and that is savings of over $50,000. 2 Reduce your overall glazing by 15 per cent Glazing is expensive says Nelson, and it loses a lot of heat at night.

“Glazing is more expensive than an insulated wall, and an insulated wall has an R-value 800 per cent better than a double-glazed aluminium

Shave 15 per cent off the floorplan of the average 182m ² house - you won’t notice if it’s done well - and you can save over $50,000.

R-values are a measure of heat loss from ceilings, walls and floors. NZ has R-values 50 per cent worse than many countries. Source: NZ Green Building Council

window. Building an insulated wall is cheap; buying aluminium doors and windows is expensive. And a bogstandard double-glazed aluminium window is a low performance product.”

You could save a lot of money following the 15-15 rules, says Nelson, but a better long-term idea would be to re-invest those savings into designing and building a smarter home.

“You could take that $50,000 in savings and plough it into high-performance windows and doors, a super-insulated ceiling, slab edge insulation, and a balanced pressure ventilation system.

“You’ll essentially, visually have the same house, your perception will be that you have the same house. But you’ll have half the power bills.”

Above: clever design features make Warren Clarke’s home appear to be much larger than 140m². We’ll have more on how Warren achieved a Homestar 10 build in an upcoming issue.

Above: this container house has most of its glazing on one side. Put most of your glazing on the north-facing side of your house, and as little as possible on the the southern side and it maximises warmth coming in and prevents it from being lost at night.