Buildings could be 20% of NZ's carbon footprint: we need to do better

“Buildings could be 20% of NZ’s carbon footprint” – NZ Herald’s Jamie Morton." 14th May 2018.

We need to do better.

Part of my role as a building scientist is to run simulations on buildings in the early design stages to predict their performance. Everything is quantified from energy efficiency, to lighting and thermal efficiency, and the comfort of the occupants. By modelling these simulations, we can estimate for example, how much a building will cost to run and provide return on investment of sustainable design for our clients.

A recent project, the new three storey 6400m2 architecture and engineering school Kahukura at the Ara Institute in Christchurch, was designed based on feedback from this type of early performance modelling. It was predicted to run 65% more efficiently than if it was designed to Building Code. The building is ‘Net Zero Energy Ready’ and the net total annual energy savings compared to an existing block on the site equates to approximately $130,000 and a respective CO2 reduction.

Pegasus Primary School, also in the Canterbury region, used building modelling early in the design for a Net Zero Energy school. The modelling assisted in designing an efficient base building, optimising efficiency through high levels of insulation, double glazing, good solar management and well considered light capture.

The building is fitted with 560m2 of solar electric panels. The efficient construction systems complement the solar panels. In addition, energy monitoring is displayed on visual dash boards for the school to consciously manage their energy use. It’s estimated 60% of energy use within the building is attributed to occupant behaviour; use of plugs, efficiency of equipment and behaviours. The solar panels feed electricity and hot water into the school and any excess ‘stored’ goes to the national grid. They generate about $28,000 of power per year (at 18c/kwh) and reduce carbon emissions by nearly 30 tonnes per year.

To put that into perspective, one tonne of carbon emissions takes 15 trees over a 30-year period to sequester. The reduction in carbon emissions made by the green design of Pegasus School is equivalent to 450 trees planted in the ground for 30 years.

We have been using this type of analysis for the last 10 years. Jasmax’s goal is to achieve 75% greater efficiency than Building Code requires. With early performance modelling it is not too difficult to explore how we can streamline operational efficiency for our clients over the 30-50 year life span of their buildings.

Currently, I’m working on modelling strategies to reduce energy use in a number of large scale residential projects. There are some important conversations happening around affordable, comfortable and healthy homes with low energy consumption.

Passive design strategies, those that capitalise on natural ventilation, heat gain, daylight, shading, orientations and site response, are of minimal cost and yet their effect can significantly reduce electricity and energy costs within a building.

There are many factors key to designing as high a performing building as possible. Early performance modelling to inform design, careful selection of materials, and finally, ensuring that we communicate the potential of these buildings.

This article is borrowed from Sarah's LinkedIn profile. View and comment here.

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