Why worry about the accuracy of building simulation in predicting

the energy efficiency of Australian office buildings

What is building simulation?• Computer-based modeling of a building• Evaluates all energy flows and the interactions

between them over a typical weather year• Calculates heating and cooling loads, and transfer

of heat between building zones at each hour through the year

• These calculations include consideration of:– lighting– plug-in equipment– occupancy – building fabric– building geometry – HVAC systems.

Commonly used building simulation packages

• IES (Integrated Environmental Solutions) Virtual Environmental

• AccuRate (for residential buildings only)• DOE2 (now superceded)• TAS• EcoTect• EnergyPlus which is what I am using

How building simulation is used in designing Australia office buildings:

• To verify Building Code of Australia energy efficiency compliance as an alternative fulfilling requirements of the highly prescriptive Section J of the code

• To achieve a pre-construction Australian Building Greenhouse Rating (ABGR)

• The ABGR Rating also forms the energy component of GreenStar rating

Why focus on office buildings:

• Between 1990 and 2005, energy usage by the Australian commercial sector increased by 65% (ABARE, 2006)

• Within the commercial sector, office buildings were responsible for the most greenhouse gas emissions, 27% of the sector total (ABARE, 1997)

More reasons to focus on office buildings:

BUILDINGS

The research I’m doing at the moment:

• Generating simulation models of five actual office buildings with anticipated 4 stars or better ABGR

• Field validation of building simulation comparing simulated results with measured data from utilities

• Identifying sources of discrepancies between modeled and measured energy use

Drawings generated by EnergyPlus of four of the buildings I’m studying

Things that are starting to look like causes of buildings being less

efficient than expected:

• Bizarre behaviour of system operators

• Fewer occupants than expected, particularly in the early morning causing much greater than expected use of heating

Actual compared with measured base building energy use– Building Two

Occupancy checks – Buildings One and Two.

Thank you for your kind attention…