Spot the differences.
Part of the job of a Thermal Performance Assessor is playing ’Spot the difference’ with a design.
A project may look great and be exactly what a client wants, but having the home with a comfortable temperature requires attention to some areas.
The above picture had a couple of items that made a HUGE difference:
The glass area to floor area was over 45% (not counting the skylights). Windows do not make great barriers to temperature conduction from inside to outside a dwelling. Also, more glazing means less room for insulation, and those windows have to become am increasingly higher quality to make up for this.
The Large amount of voids. While it is nice to have high ceilings in the entry and the kitchen living areas, it also creates a large volume of air to be regulated.These voids also often do not have openable windows to vent the build up of hot air in summer and are not always desirable to have ceiling fans installed to force air movement. The above analysis shows that the kitchen'/living zone in the model uses 32% of the energy in the house and still only achieves a 5 star rating.
These differences (among many other issues with this particular design) need to be considered. They are the things that may make the dream home impossible to build. A good thermal performance assessor can provide suggestions to help.