What is energy management with respect to chillers? Currently, the industry standard chiller energy management practice is to provide enough cooling to meet the needs of the facility while minimising chiller run hours. This is either achieved manually by experienced operators or automatically by a building automation system or chiller plant manager automation system with operator oversight. Neither of these methods addresses the enormous energy savings of increasing chiller performance and operating efficiency, though.

The Empire State Building, in New York City, is an American cultural icon. Built in 1931, it remains the fourth tallest building in the United States. It is designed in the distinctive Art Deco style and has been named one of the Seven Wonders of the Modern World by the American Society of Civil Engineers. It is ranked number one on the AIA’s List of America’s Favorite Architecture.

The building’s 10,000 RT plant includes electric- and steam-driven centrifugal chillers and is located three storeys below ground. The plant supplies chilled water to three zones: Low, medium and high. Each zone is a primary flow parallel chiller arrangement. Cooling towers are located on the ground floor in the open-loading dock area. Tim Dailey, the Director of Engineering at the Empire State Building, was looking for a way to save more energy in his facility. The Empire State Building had already been recognised as a LEED-certified building and had incorporated almost every ECM (Energy Conservation Measure) available in the industry. The chilled water plant had VFDs on all its condenser and chilled water pumps, on its cooling towers and on all its electric-driven centrifugal chillers. Additionally, it had a state-of-the-art BMS/CMS operating and controlling the building and optimising the chilled water plant, so it seemed not much was available to further save power at the building’s 10,000 RT plant. Dailey still felt that his plant could save additional energy, and that’s when he contacted US Chiller Services to have a look at his plant to see if we could do something more.

After a brief inspection of the plant, we realised we could save at minimum 15% of the plant’s energy; and with the plant maintenance being put out for bid, we thought this would be an ideal opportunity to implement retro-commissioning of the plant, should we win the bid, which we did.

The year 2017 was used as the baseline, as all ECMs were fully installed and operational in 2017 and the savings achieved were already confirmed and proven. This was the perfect baseline for us to prove the additional savings we would achieve with our retro/commissioning services, which were all performed as part of our service agreement for the plant. The sweetener was that the iconic building did not require any additional investment for any savings achieved.

In 2018, we completely retro/recommissioned the plant, paying particular attention to the electric-driven York YK centrifugal chillers. We utilised two parameters for savings verification: the chiller’s kW/ton performance and the 2017 vs 2018 utility bills, which were weather and occupancy normalised.

Major energy savings

We selected various load points of the chillers in 2017 and the corresponding kW/ton at these load points.

We selected these same load points of the chillers in 2018 and the corresponding kW/ton at these load points.

The data proved the retro/recommishing realised a 44% increase in chiller efficency.

We then compiled the full 2017 and 2018 operating data, and the retro/recommissioning proved the chillers had a 45% improvement in efficency.

We had an outside, independent party perform a utility bill analysis, which proved that the retro/recommissioning saved USD 1,344,110 in power costs.

Throughout the United States and the Middle East region, there are thousands and thousands of buildings and chilled water plants that have tremendous opportunities to save vast amounts of energy, even if they have implemented various ECMs and have already saved energy. Indeed, retro/recommissioning still have the ability to save substantially more energy.

Chiller and chilled water plant retro/recommissioning should be a major part and the first step in energy conservation. It will – as we have found and as our data proves – save the bulk of energy even over employing any other expensive ECMs at the chilled water plant and should be the major part of the solution for buildings and chilled water plants looking to conserve and save power and money. This solution is suitable for a wide range of facilities in new buildings, chilled water plants and in older facilities. For many owners, retro/recommissioning can be included in the maintenance/service agreement, and the energy savings will be an operational expense and not a capital expense. In addition to the improved energy efficiency will also come greatly improved chiller reliability, as an efficient chiller is a reliable chiller. The facilities will also have improved comfort and the ability to meet cooling requirements during peak load.