About District Cooling >> FAQ
Some of Our Most Frequently Asked Questions and Answers Include:
Q: What is the temperature of the chilled water that district cooling will provide?
A: Chilled water will be delivered at a constant temperature of 44°F, 24 hours a day, 7 days a week.
Q: Are you going to use seawater in my building? Won't that cause corrosion problems?
A: Definitely not! No seawater will be used in buildings. Seawater is only used to cool the closed-loop freshwater system. The seawater is then returned to the ocean in an environmentally safe manner. A corrosion-resistant heat exchanger will separate seawater from chilled water. The seawater and freshwater never mix. The chilled water provided to buildings is treated potable water, similar to that currently used in existing building systems.
Q: What experience does Honolulu Seawater Air Conditioning have with district cooling?
A: Our personnel have direct experience in developing Scandinavian and European projects, including Europe's largest seawater air conditioning project in Stockholm, Sweden. The Stockholm system includes approximately 80,000 tons of air conditioning load and continues to expand. Present Honolulu Seawater Air Conditioning’s personnel have recently undertaken the responsibility from preliminary design to construction and complete market concept of two Dutch systems, both located in Amsterdam with an aggregate capacity of more than 35,000 tons of cooling.
Honolulu’s district cooling’s deep water engineer, Makai Ocean Engineering, undertook the deep water side pipe design for the Toronto, Canada, and Cornell University systems. Makai Ocean Engineering was also the design engineer for the Natural Energy Laboratory of Hawaii Authority’s (NELHA) seawater pipes, located in Kona on the Big Island, that were successfully initiated over 20 years ago. The seawater pipes have since then been expanded and extended.
Q: How much will it cost to connect my building to the district cooling system?
A: The cost varies and is dependent on the building’s existing chilled water distribution system. It is generally easier and less costly to connect a building that has chillers in the basement than one that has chillers on the roof. While buildings taller than 280 ft require a heat exchanger, those less than 280 ft tall may choose to have one installed in order to isolate a building’s system. Also, if a heat exchanger is required, or desired, costs will be higher than otherwise.
Honolulu Seawater Air Conditioning will work with each building to ensure that these costs are minimized. The HECO rebate program will cover a substantial amount of these interconnection costs.
Q: How will we be billed?
A: Your monthly bill will consist of a capacity charge and an operating charge. The capacity charge is based on the annual district cooling capacity related costs divided by the aggregate district cooling system capacity (tons), and is billed in twelve monthly installments through the capacity charge rate ($/ton/month). Your monthly capacity charge is then determined by multiplying your building's capacity in tons by the capacity charge rate. Capacity related costs include all net debt service, financing costs, equity and working capital. The operating charge is based on all other district cooling system costs divided by the total district cooling system energy usage (ton-hours), and is billed through the operating charge rate ($/ton-hour). Your monthly operating charge will be your building's energy usage in ton-hours multiplied by the operating charge rate. Examples of operating related costs are: all rents/leases, labor, management, sewer and water charges, insurance, general and administrative expenses, operating and maintenance costs, and electricity charges.
Q: How reliable is a Seawater Air Conditioning system?
A: Reliability is very important for Honolulu Seawater Air Conditioning. District cooling systems are far more reliable than individual building cooling systems. With respect to the chilled water distribution system, these pipes are buried and experience infrequent problems. The district energy system in St. Paul operate with 99.999% reliability.
Q: Do we need to maintain our existing chillers and cooling towers as a backup to district cooling?
A: In general, no. You will have to maintain these systems during the changeover to district cooling. However, after the changeover, keeping your existing systems is optional. Some owners may want to keep these systems. It has been our experience that many of those who initially choose to keep their existing systems remove them after a few years once they see just how reliable district cooling systems are. Furthermore, the removal of their existing systems free up space that may be used for other purposes (such as parking spaces, etc.).
Q: What is the "down time" associated with interconnection to a district cooling system?
A: The associated down time is minimal. The final interconnection can be done very quickly and after hours, if necessary.
Q: How can I get more information about the current status of the downtown Honolulu district cooling system?
A: We welcome your inquiries. Please contact us at info@honoluluswac.com.