Good enough

Sufficiency is a concept we need to get our heads around when discussing Building Code upgrades. There is this narrative out there, that the Building Code is the minimum, and that well-meaning people need to exceed the minimum. Let me challenge this narrative. A minimum needs to be sufficient to achieve the desired outcome. If your software says that it requires a certain version of an operating system to function, it means it will not work when installed on a lower version. So let’s discuss which outcomes we want for buildings that house people. The Building Act is a good starting point for this. Purposes listed are safeguarding that buildings have attributes that contribute appropriately to the health, physical independence, and well-being of the people who use them and that they are designed, constructed, and able to be used in ways that promote sustainable development. Compliance with the Building Code is viewed as elemental in achieving these purposes – the Building Code, therefore, needs to have provisions that are sufficient to affect these outcomes. As we all know, that is not currently the case. So, what is good enough to turn the mandate of the Building Act into results?

Clare Parry – Director Sustainability at Development Victoria – made some excellent points in a recent LinkedIn post:

Passivhaus is a measure of minimums. It's NOT over-engineered, stringent or an exercise in maximising what can be done.

The minimum you need to do to avoid the risk of mould and condensation.

The minimum you need to do to avoid discomfort from radiant temperature of your envelope.

The minimum you need to do to make sure your occupants *always* (not just sometimes) have adequate ventilation, and that it's filtered from outdoor contaminants. And that the system is kept clean, all the time.

The minimum you need to do to ensure that your heating and cooling system is the size it should be (not has to deal with substandard approaches for the stuff above).

The minimum it should be to enable a climate-appropriate response.

So when someone comes and asks for a building to “Passivhaus-principles", what they really want to know is ... which bit don't they have to do?

Well, you choose - which compromise do you want to make?

I fully agree with these points when we consider the effects on the well-being of people who use buildings. Expanding on the required climate-appropriate response, I suggest that as a minimum, we need to give effect to international treaties, which are reflected in our own laws. The Climate Change Response (Zero Carbon) Amendment Act 2019 has as one of its purposes to “contribute to the global effort under the [United Nations] Paris Agreement to limit the global average temperature increase to 1.5° Celsius above pre-industrial levels”. According to BRANZ research, houses built to the current Code exceed the carbon budget for compliance with these obligations by several multitudes. We cannot comply with our international obligations by adding a few millimeters of insulation here and there. The Code needs an overhaul to consider the whole story of heat exchange between a building and its environment. All that’s considered in H1 is transmission heat loss. It is also not considering the wider environmental impact of the ways we heat houses or generate hot water. There are international standards readily available that do – we need to use them.