An iconic building like the Empire state was responsible for 25,000 tons per year of Carbon dioxide emissions, and the 102 stories cost $11,000,000 in annual energy, prior to 2008. This was all before the building went through an exercise of determining cost effective Energy retrofit solutions, while reducing operating costs.
The exercise started with over 60 ideas for energy efficiency that were narrowed down to 17 projects. The 17 projects went through a further analysis based on greenhouse gas savings, dollar to metric ton of carbon reduced and an estimate of minimum energy usage. Implementation was narrowed down to reducing loads, using efficient technology and providing control. This exercise sets a very good example for San Francisco architects to implement in Energy Retrofit projects locally.
$500,000,000 was spent on energy related projects, such as lighting controls, chillers etc., pay back is established at 3.1 years. Initially, the team thought that they will need new chillers for the hallways, but the result of combined measures took care of the stuffy hall ways and common areas, making them more livable and thermally comfortable. Most all the measures described below are very doable for all bay area architects in local large scale energy retrofit projects.
Eight measures included:
- Radiative Barriers: Six-thousand insulated reflective barriers were installed behind radiator units located on the perimeter of the building.
- Chiller retrofit of four industrial electric chillers in addition to upgrades to controls.
- DDC controls: The measure involves upgrading the existing control systems.
- Day lighting & Plug Load Occupancy Sensors: Lighting power density in tenant spaces is reduced by installing dimmable ballasts and photosensors for perimeter spaces, which get plenty of daylight. Plug load occupancy sensors were also provided for occupants’ personal workstations.
- VAV air handling units replaced existing constant volume.
- Window retrofits: Serious energy set up a processing facility on the 5th floor to improve the efficiency of the existing 6,514 windows by re-using all glass. The building’s existing aluminum window frames with R1 value for insulation were also re-used. Major labor cost involved cleaning the existing windows which took 2-3 hours for each panel. Existing glass panels were removed, cleaned and super -insulated improving the R-Value from 2.1 to 7.6 and reducing SHGC from .72 to .49 in some examples. Re-using glass and existing frames with improved energy efficiency cost $4.5 million, which is $15.5 million less than the cost of new windows. Setting up a processing space on 5th floor reduced waste and emissions, that otherwise happen in off-site operations.
- Tenant energy management: The intent is to demonstrate design principles for all tenants to practice.
The Empire State Building project team Johnson Controls Inc., Jones Lang LaSalle, and Rocky Mountain Institute’s combined effort will eventually save 38 percent of the building’s energy and $4.4 million on utility costs annually. This effort has improved the property value and further will help reduce 105,000 metric tons of CO2 over the next 15 years.
Result is an enhanced work environment with better thermal comfort and improved indoor air quality because of radiative barriers, windows, occupant control and better lighting conditions. The project earned LEED Gold status for EBOM and Energy Star label, not to mention a remarkably positive return on investment and is an outstanding example of Energy retrofits for existing and historic buildings.