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New York City, New York 

emp1The famous Empire State Building is a recognizable landmark. First built in 1931, it was the world’s tallest building for many years. Today it is the tallest building in New York City – 102 stories and 1,250 feet high. This huge building contains 2,800,000 square feet of office floor space in midtown Manhattan.

As part of an ongoing overhaul and renovation of the building costing $500 million, $20 million will be spent on improving energy efficiency. These improvements will reduce the building’s energy use by 38% and save the building owners $4.4 million per year. The investments in energy efficiency will pay for themselves in less than 5 years!

Work began in 2009 and will be complete in 2013.

With no practical opportunities for on-site power generation of any kind (renewable or non-renewable sources), energy savings are achieved entirely through demand reduction – more efficient use of the energy resources employed. An integrated approach to the design of the building renovation has achieved these significant savings in the following ways:

  • Reducing Loads: The building’s 6,500 double-pane insulating windows were removed and rebuilt to include a third layer of glass and a reflective film. Heat loss through windows is reduced to a third of previous, and solar heat gain is cut in half.

More than 6,000 radiators along exterior walls of the building will be fitted with heat-reflecting barriers behind, to reduce heat lost directly through the wall.

Electrical loads will be reduced by the installation of more efficient lighting that is dimmable and automatically controlled for day lit spaces.

  • Efficient Technology: Because of the reduced cooling load (solar gain reduction and reduced lighting), a smaller air-conditioning plant is required. This meant that energy-efficient modernizations could be made to the existing equipment, rather than replacing it.
  • Controls: State-of-the art digital monitoring and control of building systems will be used. Sensors will automatically monitor the need for fresh air, reducing heating and cooling loads by reducing the amount of fresh air brought into the building to only that which is necessary

Most importantly, individual tenants will now be metered separately for electricity use. They will now be responsible for their own consumption and electricity bills, meaning that they will be directly affected by their own savings or waste, rather than the landlord. They will have access to the building’s energy information, and be able to compare their use to average high and low performers in the building to understand how they are performing.

For the energy retrofit, the greatest cost savings comes from the ability to retrofit the existing air-conditioning plant rather than replacing it. This is made possible by the substantial reduction in cooling loads, and is a significant factor in the favorable payback calculation.

Peak electrical demand will be reduced by 38%.

In addition to cost savings and greatly reduced pollution and greenhouse gas emissions attributable to the building, the renovation will deliver an enhanced environment for tenants, including improved air quality, better lighting conditions, and superior thermal comfort resulting from better windows, more efficient radiators, and individual controls.

This project is an excellent example of how significant energy savings can be realized through the following simple steps:
  • Reduce Loads
  • Install Efficient Technology
  • Improve Controls

An additional interesting aspect of the project concerns the upgrading of the existing windows. Firstly, by repairing and re-using existing windows rather than replacing with new, much was saved in terms of materials and waste. Secondly, a shop was created on-site to perform the work rather than removing the windows to a remote location; saving hundreds of trips by truck, energy and costs. Savings in materials always equate to reduced embodied energy, as does reduced material transportation. In this case, these energy savings were not factored into the energy savings and payback calculations, but are obviously significant!

Adapted from High Performance Buildings, Spring 2010, pp. 20 – 32.