House 1

Back to Existing Homes

Before renovation

House 1 belongs to a family with a preschooler and a primary school child.  It is a split-level three bedroom house, typical of the 1970s, where homes were not designed to be facing the sun.  The skillion corrugated iron roof with exposed ceiling rafters was also common  in this era and was thinly insulated (approx R1) over the upper two levels.  Split levels were popular at the time and can be complex to renovate as they generally include a variety of building materials and systems.  The home has a mixture of sheet and weatherboard cladding, and while the upper floors have a timber suspended floor, the lower storey has a concrete slab floor which, without insulation, leaks heat into the ground.   The windows in all rooms but the master bedroom were timber-framed and single glazed, and draughts are noticeable at times.

A woodburner was used to heat the open plan living areas in winter, while oil column heaters were used to heat bedrooms two and three. 

The family found the house cold in winter – particularly in the children’s bedrooms. They wanted to save money and create a healthier home for family members suffering from asthma.

The renovation package

House 1 received a standard thermal retrofit with efficient heating and a heat transfer system.  This included:

  • lowering the skillion ceiling and installing R4.6 insulation 
  • insulating the suspended floor with R2 foil-backed bulk insulation
  • covering the under-floor with polythene
  • draught stopping the door to the garage
  • adding R1.1 hot water cylinder wrap and 15mm pipe lagging
  • replacing the older woodburner with a pellet burner
  • ducting a heat transfer system into bedrooms 1, 2 and 3
  • using compact fluorescent bulbs for main lights
  • a plumbing maintenance check
  • a worm farm

Improvements as a result of the renovations

A warmer home

Temperatures in the family room and main bedroom improved significantly as a result of the measures.   Average winter temperatures in the family room increased by 1.1°C.  Average winter temperatures in the main bedroom increased by 1.5°C.

These temperatures are given as averages (mean), and as the overnight temperatures are still low, it brings the average temperature down. 

However, looking at the most common temperature experienced in winter in the family room and bedroom, we can see a  ~2°C increase.  The temperature most often recorded in the family room before renovation was 14°C; after renovation, it was 16°C.  Likewise the bedroom moved from the most common temperature of 13°C to 15°C after renovation. The heavy ceiling and under-floor insulation has helped retain the warmth in the home with more efficient heat being produced by the new pellet burner.  Bedroom temperatures have improved with the heat transfer system taking heat to bedrooms.

Lower power bills

The family’s electricity use reduced slightly - largely as a result of the improved efficiency of the hot water system from wrapping the hot water cylinder and lagging the pipes.  Overall they used significantly less electricity to heat their water with a reduction of 12% in hot water energy use during winter.

This contributed to an overall reduction in the family’s electricity use of ~7% over winter.


What the family found

The family were keen to renovate to save money and make their home healthier for family members suffering from asthma.

The family were pleased with the warmer winter temperatures in the living areas although they quite correctly still described the children’s bedrooms as cold. 

The pellet burner has been successful in warming the living areas – the family describe it as extraordinarily efficient, convenient, ‘guilt free’ and safe.  In fact they increased the level of warming in the family room, running the pellet burner from 4 pm to 10.30 pm in winter.  They did, however, find that the pellet burner was noisy and felt that the costs of pellets were high.

The family did enjoy their new worm farm, especially for its interest for the children.

Our analysis

When this home’s performance is measured against the benchmarks of Beacon’s HSS High Standard of Sustainability®, it could still perform better for the family. 

We believe that homes should be heated to a healthy indoor temperature.  By using the pellet burner more often and for longer, the temperatures have been raised, while energy costs have remained the same.  However, despite the increases in temperatures, both the  family room and the main bedroom remain below the HSS High Standard of Sustainability® benchmarks.  The average minimum winter overnight temperature was 13.2°C in the main bedroom, and the average 24 hour winter bedroom temperature was only 14.7°C.  Our benchmarks, based on World Health Organisation recommendations, set a minimum of 16°C overnight in bedrooms and 18°C in the evenings for family rooms. Warmer indoor temperatures would be reached by draught stopping windows, using thick curtains and pelmets, adding wall insulation  and double glazing windows, especially south facing windows.

Humidity, the percentage of moisture in the air, is recommended to be between 40% and 70%.  Humidity levels were tested in July and found to be above 70% three quarters of the time.  Humidity is linked to the cold indoor temperatures, as cold air holds far less moisture than warm air.  In cold temperatures the moisture naturally in the air settles on cold surfaces such as un-insulated walls, ceilings and windows as condensation.  Condensation and cold are the perfect conditions for growing mould which thrives in humidity greater than 70% on cold surfaces with condensation potential.  Increasing indoor temperatures and getting rid of indoor moisture (installing a kitchen rangehood and bathroom extractor fans would be a good start) will keep mould down and make the home healthier for asthma sufferers.

The household’s electricity use remains high at around 11,000 kWh per year.  The benchmark for electricity use is 7300 kWh per year.  We would suggest installing a solar water heater to reduce water heating costs.

Apart from the plumbing check, no measures were undertaken in this house which would be expected to impact on water use.  The household average per person water use was a fairly high 287 litres/pp/day compared to the benchmark of 125 litres/pp/day.  Replacing the full flush toilets with dual flush toilets would address this.

Next: House 2

House 1, Papakowhai