Increasingly, we hear claims that buildings are “green” or sustainable, with carbon neutral impacts and the like.

In the recent past, these terms were optional add-ons for an interested few, but now it seems to be essential for many companies to be seen as green, eco, or sustainable.

However, what do companies mean when they claim to be sustainable, or their buildings are net zero, or their activities attached to a carbon offset? It can be confusing, as these terms are fluid, or appear to be coined on the run, without a unified definition. And it gets even more confusing when we have a variety of certification and rating systems which apply sustainability “stars” to our buildings.

Let’s look at the terms “net zero” and “carbon offset,” starting with some popular definitions courtesy of Wikipedia, the font of all dictionary-type knowledge.

A net zero energy building is defined by Wikipedia as “a building with zero net energy consumption, meaning the total amount of energy used by the building on an annual basis is roughly equal to the amount of renewable energy created on the site…these buildings do at times consume non-renewable energy and produce greenhouse gases…

"Most zero net energy buildings get half or more of their energy from the grid.”

In other words, your building consumes x amount of energy, and your site creates x amount of energy, so you claim your total is zero.

Note the difference between building and site. It is not the case that the building makes up for its wastefulness in energy consumption, which is why some have made the point that net zero isn’t the sort of goal we should be aiming for.

That’s because you could set up a nuclear power plant in your back yard, tell people it is part of your “building” or that it will “make up for” the energy used by the building, build a really leaky, poorly insulated, badly designed, cheap, drafty, mouldy building, which consumes a lot of energy to condition the inside, and spews the energy out the walls into the atmosphere; and call the whole thing net zero.

It may in fact be net zero, but it would be very bad for the environment, for your carbon footprint, and for climate change (not to mention unhealthy and uncomfortable.)

This kind of confusion has led to another term: “greenwashing.” This is defined by Wikipedia as ”a form of spin in which green PR or green marketing is deceptively used to promote the perception that an organisation’s products, aims or policies are environmentally friendly.”

A well written publication on this topic, The Carbon Neutral Myth – Offset Indulgences for your Climate Sins, published by The Carbon Trade Watch in the Netherlands back in 2007, makes the point nicely:

“Most offset schemes take the following approach. A simple calculator on a web-site shows the quantity of emissions produced by a certain product or activity. The customer can then choose from a variety of projects that promise to ‘neutralise’ an equivalent amount of emissions by energy-saving, or through carbon absorption in trees. The consumer pays according to the claimed project costs and the amount of emissions to be ‘neutralised.’

“The sale of offset indulgences is a dead-end detour off the path of action required in the face of climate change. There is an urgent need to return to political organising for a wider, societal transition to a low carbon economy, while simultaneously taking direct responsibility for reducing our personal emissions. “

And, to take carbon offsets offered by our airlines when we fly as an example, the writers say “the idea of achieving climate neutrality through offsetting is no more than media spin. First, it takes 100 years to fully cancel out the carbon effect of one aeroplane flight.”

I used to think that by paying a few dollars to the airline as a “carbon offset”, I could fly with a clear conscience knowing that I had not contributed to climate change. Looks like I was duped.

Similarly, The Carbon Neutral Myth debunks the notion that planting a few trees will sufficiently “offset” the effect of the energy consumption of a new building.

It’s complex, but one of the problems is how long the trees need to grow, before they start making a real impact. In the meantime, the inefficient building has pumped out the proverbial in carbon – for quite a few years. It’s not a decent ”offset” if it takes years to kick in. We don’t have the luxury of years.

But it sounds so simple, so mathematical, so certain - "net zero" and carbon "offset." Can’t I absolve my building sins by planting a few trees or adding a few solar panels?

The thing about “net zero” type claims is the risk that we believe them because they are presented as mathematical calculations. It's easier for us to believe them than analyse them.

Solar panels on my roof isn’t going to make my building carbon neutral, or net zero, or carbon positive. It’s not going to make my heating system and leaky building “green.” Even if it reduces my bills, it doesn't mean my building is efficient. Nor does planting a few trees.

This is why we need to face the energy consumption of our buildings squarely, before we consider the add-ons. We need to address the kinds of things that are identified for the Passive House Standard - draft free, not leaky, with clean incoming air, heated up by re-using the heat from the stale air which is being extracted. No condensation or mouldy conditions. A building that reduces energy consumption for its life because it traps energy naturally produced inside.

We don’t need to consider a false calculation called an “offset” or a pretend mathematical equation that tells me we’ve paid for our sins and achieved a “positive” status, or even a neutral one, in order to design a building that uses less energy.

Everybody should consider proper “near zero” energy building design through design tools like the Passive House Standard.

Considering the use of more sustainable materials, like timber from plantation trees, is important, where possible, as is the installation of solar panels and other forms of renewable energy instead of coal, where possible. But it's important to analyse claims and see what is meant by the person making them.

It's important not to disguise the different issues we need to face right now, such as efficient, robust, future proofing building design which consumes less energy.

No faulty maths. No greenwash.

  • Sorry but this article is "Passiv-washing" – a Passivhaus does nothing for running TVs, fridges, computers etc so this comparison is comparing oranges with apples. Passivhauses will generally draw more from the grid than a Net Zero Energy or Net Zero Emissions home, as in Passivhaus there is no requirement for any renewables (except the recently extended Passivhaus+). Given that heating/cooling is close to 20% of total electricity demand in a new six-star home, reducing that to almost nothing like a Passivhaus does while still leaving the rest of the 80% untouched is generally not cost-effective & obviously will never achieve zero emissions!

    • Hey Rob
      Passivhaus does take into account total energy demand. Just check out passipedia.
      As for renewables, have another read of the article above!

    • Fiona, you haven't shown how a Passivhaus provides any greater greenhouse emissions benefits than just reducing the 20% heating/cooling demand we see on 6-star homes to close to 0% (while adding in things like ventilation electricity demand from a HRV). Renewable energy systems are certainly required for the rest of electricity demand.

      The Passivhaus 120kWh/m2.yr primary energy demand is not even close to net zero emissions. The fact that PHI have added in the Passivhaus Plus categories that require renewable energy argues exactly my point.

      Your article says "Solar panels on my roof isn’t going to make my building carbon neutral, or net zero, or carbon positive." While you can argue about the embodied energy of PV systems with their 4-5 year+ embodied energy payback (something that Passivhauses also have significantly more of than standard homes due to extra foam insulation, steel, glass, timber, HRV systems etc – in fact our calculations show that this embodied energy payback for PHs can sometimes be on the order of 20 years+ because you are chasing diminishing returns) in the end, to run appliances, lighting, etc renewable energy systems are essential – and the end goal for integration of these systems is zero or positive emissions, with net zero emissions being a good starting point.

      Certainly it is our opinion that Net Zero Emissions for a house is a much more appropriate environmental goal than Passivhaus, which while having energy efficiency attributes, in some respects is more properly judged an indoor environment quality (thermal comfort & air quality) system.

  • Hi Rob
    I'm not sure who you represent or what research you have done.
    You say the passivhaus energy standard is "not even close to net zero emissions". My article is criticising the net zero equation. Not claiming that passivhaus is close to net zero. You can say it's near zero but the concept of "net" is a concept I am criticising, not aiming for.
    The passivhaus new categories ADD renewables and the like TO the passivhaus standard. They don't compromise it. They don't support your view, to the extent that your view is clear.
    My point about solar panels is that you can add them to a house, to a backyard, to a neighbour's house, or a field down the road. They are nothing to do with the house. They are nothing to do with the energy efficiency of the house. Have a look at Lloyd Alter and Elrond Burrell on this aspect. As well as the Passivhaus Institute itself of course!
    When you say "Certainly it is our opinion" I don't know who is certain or who "we" are. Your comments are a little confusing and I suppose are an example of the kind of thinking my article addresses.

  • Thank you for your article, Fiona. However, I feel that in labelling net zero energy buildings as "greenwashing", you go too far. Where I live, in subarctic Edmonton, Alberta, you have to build a darn efficient building to attain net zero status. Net zero buildings here use mostly solar PV, and some ground- and air-source heat pumps as an energy source. Due to the cold climate, you have to build a super-insulated air-tight home with HRV to have any chance of being net zero (and no-one has a mini nuclear station in their backyard … 🙂 Carbon offsets are never as good as not creating GHG emissions in the first place. But if they come from a reliable, CDM certified source, they are perhaps the next best thing where emissions are harder to avoid, e.g. flights for car travel. Where I do have to agree with you is that net zero doe not include any (high) performance standards, or look at WHEN the energy created (e.g. in Alberta a home uses most energy in winter, but produces most energy in summer). I DO like the PassivHaus performance standard, and if you do decide to add PV later, you know you have gone as far as feasible to build on a solid, high-performance platform. So, I agree with your praise of PassivHaus and high performance standards, but think that calling net zero buildings "greenwashing" probably goes too far.

    • Thank you Godo. Very interesting comments! I wasn't saying that all net zero energy building claims are greenwashing, just that this kind of phrase can mask the fact that a poorly designed, inefficient building is sitting there under a green roof and solar panels. In Australia there are very few buildings as good as what you describe in Edmonton. So net zero type claims can be bandied about when the building is not very efficient. I fully agree with you that "Carbon offsets are never as good as not creating GHG emissions in the first place". In Victoria, Australia, we have to face the fact that we are using dirty coal for much of our power (or diesel, in Tasmania, see my last sourceable article!) so of course the power source is relevant to all these assessments. Passivhaus is barely beginning to be understood in this country, and it will be great to see more recognition of it.