BUILDING CASE STUDY REFURBISHMENT
air handling units, chillers and glazing could each save 5%. Tenant energy management, including access to online benchmarking tools, could save 3%. Finally, the addition of a radiative barrier and tenant demand ventilation based on CO2 sensors could each save 2%. The building energy model will be used in conjunction with utility, weather and usage data, tracking savings each year to determine if targets have been met. If they have not, Johnson Controls will pay the owners for the shortfall. The savings are guaranteed for 15 years. As aggressive as Malkin and his team
Some of the biggest financial savings are expected to come from the upgraded chiller plant
was economically possible to reduce energy consumption by 38% and save 105,000 tonnes of CO2 over 15 years. In January 2011, Malkin agreed to buy carbon offsets totalling 55 million kilowatt hours per year of renewable energy, making the Empire State Building carbon-neutral, according to the company. The greatest reduction in CO2 emissions
at the Empire State Building is expected to come from upgrading the control systems to Johnson Controls’ Metasys building management system. The strategy is predicted to reduce energy use by 9%. Encouraging tenants to make better use of daylight and plug-load management will aim to save 6% from the energy baseline; while upgrades and enhancements to the
were toward energy-reduction opportunities under their control, the success of the programme will also rely on actions taken by the building’s tenants. The owners and the tenants are implementing the longer- term projects, which need to be coordinated with tenant turnover. These are some of the most cost-effective energy saving measures when coordinated with planned equipment replacement. Figure 1 shows cost and projected energy savings for each measure. The total energy savings are predicted to be $4.4m, representing a payback period of three years. The Empire State Building, whose retrofit
is due for completion in 2013, recently received LEED Gold certification. It also has an Energy Star rating of 90. Anthony Malkin is being recognised for his input by the US Green Building Council, which is awarding him its Leadership Award 2011. As Campbell puts it: ‘Through this project we have proven that you can teach an old building new tricks and cost effectively move it to the top 10% of all commercial buildings in energy efficiency.’
Empire State Building Eight steps to a cost-effective refurbishment
Reduce loads: Windows The 6,500 existing windows were upgraded by removing the sashes from their frames and replacing them with a temporary window. The windows were then taken to a workshop set up on the fifth floor, where they were dismantled and cleaned. A new super-insulated glass unit was created by taking one of the original panes of clear uncoated glass, laying a warm edge spacer
32 CIBSE Journal November 2011
on it and then a suspended low- emissivity film to help reduce solar gain. Another edge spacer was
added so that the outer glass can be laid on top, creating a triple-glazed unit from the reused components, to the same dimensions as the original. The assembly is then baked in an oven for about 90 minutes to shrink the film, turning it taut and translucent. The process improves the
window’s thermal performance from a U-value of 0.5w/sq m K to 0.125W/sq m K, while halving solar gain.
Radiative barrier More than 6,000 insulated, heat-reflective barriers will be installed behind the building’s perimeter radiator units.
Tenant daylighting, lighting and plugs This measure involves
reducing lighting power density and energy use in tenant spaces by making better use of daylight and task lighting, and by installing dimmable ballasts and photosensors for perimeter spaces to link lighting to daylight levels. It also involved providing tenants with a plug load occupancy sensor to turn desk-top devices on and off depending on whether they are at their desk. The owners have also pre-built
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