Energy Efficient Homes - It's time to change our approach
by Editorial Team - Build Your Dream
Energy efficiency means more than just cheaper fuel bills, firstly and most importantly our homes need to be a healthy place to live.
The World Health Organisation (WHO) states a residential house needs to have a minimum air temperature of 16 degrees C, a building that is colder over long periods will have various problems such as condensation, damp and mould growth which create an unhealthy environment. The NZ housing stock as a whole is of a third world standard and surprisingly across all social economic groups.
The ideal living temperatures are approx. 16 degrees C for sleeping, 18-20 degrees C active living and 21-22 degrees C for static living (i.e. Reading , watching TV etc.).
If we (or via government) invested in our homes to W.H.O. standards and with solar panels, overnight we would reduce the need for more power stations, transmission lines, reduce CO2 emissions and power prices as well as remove many waiting lists in hospitals.
Every house in existence or in development in NZ can achieve the ideal living environment, with the ideal living temperatures above, there is a simple equation to work out, between the energy supply and the energy demand of each house.
The demand of a house is made up of a host of elements including location, position, orientation, size, construction type, insulation levels, ventilation, window sizes and window construction. as well as how many people live in the house.
Any Heating engineer worth his salt will take into account all the elements that makes up the demand of the house and correctly size heating/cooling equipment for the supply.
So by reducing the demand of your house by building it towards the winter sun (passive solar) or increasing insulation levels or fitting good quality double glazing you are achieving a healthy living environment with less or no additional heating/cooling equipment.
The good news is that you can now buy energy efficient houses and solar (& other effective) heating/cooling systems off the shelf in NZ, to suit your needs, that can supply the perfect living environment with low running costs.
The Greentech Design system
Greentech Design has established this system to improve the energy consumption of every residential building in NZ.
Pooling all resources from personal experiences, local heating engineers and solar experts, incorporating research written by BRANZ (& others) and data from NIWA.
Greentech Design recognises World Health Organisation criteria for healthy living standards, and calculates warm comfortable temperatures that must be achieved in the total house System’.
The System starts by establishing the energy demand of the dwelling using BRANZ ALF software, which takes in consideration many variables including location, orientation, passive solar and even number of occupants. The System recommends improvements to a level the owners and designers are happy with. 90% of designs have there demand level halved using these recommendations.
Next stage is to calculate the dwellings active solar generating capabilities for space heating, most energy efficient homes can be heated almost entirely from Solar heating by building in a storage medium (like gravel under concrete slab on grade) to help heat house on cold overcast days.
The System then equates the generating capacity against the dwellings demand, If there is a short fall then we size an additional heating source (and relevant type) to achieve desired comfort target.
The System will calculate a dwelling heating source’ if there is limited solar gains and match construction choice and heating type.
Energy efficient design requires lots of little improvements rather than one big one so, the System recognises the appropriate time to add extra energy efficient devices, like Heat Recovery Ventilation Units (HRV) and argon gas filled double glazing.