Carbon Neutral Buildings – Myth or Reality?

With the trend towards going carbon neutral terms like Net Zero Emission Building or Nearly Zero Energy are being thrown around and are causing some confusion in the industry. But what does carbon neutral or zero emission buildings mean for asset owners and developers?

The Australian Government Department of Climate Change and Energy Efficiency states that carbon neutrality refers to where the net emissions associated with organisations activities are equal to zero. This can be through the acquisition and retirement of carbon offsets.

A carbon neutral building is typically where the yearly operational energy consumption of the building are equal to zero through a process of reduce, re-use, re-cycle and offset. This takes into consideration building incorporated (or base building) energy consumption and is consistent with the ASBEC recommendation of the definition of a “zero carbon building”.

The NABERS scale has recently been extended to provide better resolution to the upper end of the scale by introducing 6-star ratings, representing market leading performance is reflective of the industry pushing the boundaries. A 7 star rating which is still under consideration would represent a theoretical carbon neutral operation for a building.

For example, a 5-star NABERS base building energy rated commercial building in the Brisbane CBD has emissions of around 60 kgCO2/m2/annum. This is a particularly energy efficient building and this can generally be achieved through good design and operational strategies utilising solely grid electricity to building systems.

In essence a 6-star rating represents a significant 50% carbon emission reduction over a 5-star building and will drive more efficient systems and operation as well as the fuel mix used for our buildings. However, this does not consider the whole lifecycle of the building which includes the following emissions:

  1. embodied energy in buildings – or the energy consumed in the materials and manufacturing used in the creating of building. This is suggested to be anywhere between 11 -23 years of operational energy
  2. occupant emissions – or the operation of appliances and other tenant/occupancy systems
  3. upgrade emissions – or emissions associated with renovations, refurbishments within the building
  4. transportation emissions – transport emissions associated with the operational requirements of the building, such as waste transportation, transportation associated with providing supplies and services to the building,
  5. deconstruction/decommissioning emissions – or the emissions associated with the deconstruction and decommissioning of a building at the end of its lifecycle, including the waste management process.

The next step for building emissions systems is to factor in the construction, occupancy and deconstruction emissions and encourage building owners and managers to measure and offset them. ADG is currently funding a Master program at the University of Queensland researching the benchmarking of emissions through these stages looking to make a carbon ratings scheme that looks at building across a whole and true life cycle including construction and decommissioning.