BUILDING CASE STUDY REFURBISHMENT
Windows are replaced and resealed to increase the energy efficiency of the building
You can teach an old building new tricks and cost effectively move it to the top 10% in energy efficiency
reduction in cooling load of 1,600 tonnes as a result of, first, the window refit reducing solar gain, and, second, a separate demand control ventilation project, which reduced the amount of fresh air needing to be cooled. As part of the process of deciding which
strategies to implement, the team had to factor in the length of time it would take to implement each strategy because of its effect on the payback period; if a strategy with a short payback took a long time to implement, that would affect the cost-benefit equation for that strategy. While the team worked out which solutions
were the most cost effective, Johnson Controls documented tenant energy usage for the building’s 1,000 businesses and 21,000 employees spread over the 200,500 sq m of office space. The third phase of the initiative centred
on modelling the whittled-down solutions using the US Department of Energy’s eQuest
Figure 1: Empire State Building refurbishment: costs and projected savings for key measures Project description
Projected capital cost
Windows
Radiative barrier DDC controls
$4.5m $2.7m $7.6m
$5.1m
2008 capital budget
$455,000 $0
$2m
Demand control vent Included above $0 Chiller retrofit VAV AHUs
$47.2m Tenant daylight/plugs $24.5m
Tenant energy management
Totals $365,000 $91,965,000
$22.4m $44.8m $16.1m $0
$85,755,000 Source: Lessons Learned: Retrofitting an American Icon, Anthony Malkin $4m
$2.7m $5.6m
Incremental cost Estimated annual savings
$410,000 $190,000 $741,000
Included above $117,000 -$17.3m $2.4m $8.4m
$365,000 $6,165,000
$675,000 $702,000 $941,000 $396,000
$4,172,000
Energy Model to obtain a cost-benefit analysis for the various proposals. Speaking at the launch of the project, Iain Campbell, vice- president of Johnson Controls, described this as a ‘state-of-the-art computer model that was able to simulate the energy performance of the virtually infinite number of combinations of the identified improvement measures, and then evaluate them from both a carbon reduction and financial return perspective’. The sustainability team produced a
matrix of costs and financial benefits. These were integrated with sustainability ratings, architectural programming and operational best practices to gain an understanding of how different strategies, implemented individually or in combination, would affect project cost and building performance. According to Campbell: ‘This allowed us to identify the optimal combination of improvement measures and then evaluate them from both a carbon reduction and financial return perspective.’ More than 60 ideas were vetted before
being eventually whittled down to eight. The reduction was achieved by looking at measures that would reduce both cooling and heating loads, such as: upgrading the windows; seeking to maximise the efficiency of the plant; and implementing a control strategy so that the equipment was used only when needed (see ‘refurbishment’ box). The final phase of the sustainability
review culminated in the production of the masterplan. Retrofits typically reduce energy consumption by 10% to 20%, but over an eight-month period the team had determined that, at current energy costs, it
30 CIBSE Journal November 2011
www.cibsejournal.com
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