University of Toronto
    RDH Building Science

Designers today, in response to codes or voluntary “green building” programs, are increasingly concerned with Energy-Use Intensity (EUI) targets. Building form and building orientation may be powerful drivers of energy efficiency – but few studies have quantified their effect. We designed a series of prototypical office buildings to show how much these and other architectural strategies reduce EUI in Toronto. Our eight prototypes ranged in gross floor area (12,000 sf to 160,000 sf) and plan form (square, slender, and H-shaped). We tested each with four levels of enclosure performance (code-compliant to very high performance) and three window-to-wall ratios (20%, 40% and 60%). Setting climate-control systems as constants, we used eQuest to predict annual EUI and month-by-month end-use.

Plan form alone penalized EUI by less than 3%. Building orientation alone had a negligible impact. A 20% decrease in the window-to-wall ratio (WWR) reduced EUI by roughly 5%. Significant upgrades to the thermal resistance of the enclosure reduced EUI by nearly 40%. Applying all measures in concert had a cumulative – not a synergistic – effect, driving the EUI of an “exemplary” building to roughly 60% of the level predicted for a similarly sized “market-level”, nearly-code-compliant building.

Note: This paper was presented at the 14th Canadian Conference on Building Science and Technology. It is copyrighted by the authors and is published with permission.

RDH Building Science