The large stock of high rise buildings built during the 60s and 70s are nearing their planned retirement. Many would argue that these buildings have many good years ahead and that the notion of a half-century design life was a stupid idea in the first place. Most can agree that these, largely glass-clad buildings, are not performing to today’s expectations for energy consumption. Last week I attended a seminar sponsored by the Chicago Council for High Rise Buildings which posed the question, “[what to do with aging mid-century] high-rise buildings: renovate, re-purpose, or replace.” In large part the panel agreed that renovation and re-purposing were viable, and the talks focused on improving energy performance.
The most positive take-away from the seminar was the reassurance that architects, engineers, building managers, and city officials are taking steps to address energy performance in existing high rises. The negative is that too little data is available to comparatively evaluate the performance of individual buildings. All that may be about to change. Chicago is one of a handful of cities that have passed ordinances requiring buildings above a certain size to publicly share information about their energy consumption. The bench marking ordinance is meant to provide information to planners and designers in the hopes of engineering a more efficient city. And if a little friendly competition for improving energy performance breaks out among buildings, well that’s a good thing too.
Advocates of the ordinance like to imagine that the city’s mega towers, like Willis Tower (formerly Sears Tower), will be motivated to take action. However, we learned from architect Sara Beardsley of Adrian Smith and Gordon Gill Architects, that the building owners had already considered energy upgrades. Ms. Beardsley’s team estimated that a 20% energy savings by replacing the 40-year old cladding. Unfortunately, a facade replacement is an enormously expensive up front cost. More easily within reach is replacing the buildings elevators with machines that are now 50% more efficient. That would save almost 5% on total building energy consumption!
Several speakers returned to the common refrain of trying to justify upfront facade replacement costs for long-term savings. In many buildings, like the iconic Marina City, the inefficiency extends beyond the old single pane glass to the metal mullions which readily conduct heat through the enclosure. Mr. Matthew Herman of Buro Happold described a new measure of performance that attempted to incorporate the added economic impact of a facade upgrade, beyond just the energy savings. He reasoned that a better performing facade can add value to the property by making the space more desirable. Owners should try to consider this economic opportunity in addition to utility bill savings.
The owners of 475 Park Avenue, New York were convinced of the benefits of a new facade. While the new glass curtain wall has insulative properties more than 100% better than the existing, the main driver of the investment may have simply been aesthetics. Separately, a study by researchers at the University of Southern California polled professionals involved in renovation projects. 74% of the respondents identified aesthetics as an important reason for intervention in the building facade. Here’s to hoping that more owners are motivated by the attractiveness of energy performance.