Located in Sacramento, CA
10,000 s.f. facility
Annual Cash Savings: $5800
Annual Energy Savings: 68,571 kWh
Prevented 82,423 pounds of pollution
Sacramento Municipal Utility District (SMUD)
6301 S Street, MS A204
Sacramento, CA 95817
The Rancho Murieta Association oversees a gated community with many public buildings and large grounds. This includes buildings, lakes, roads, parks and recreation areas, and a child care facility/preschool. Greg Vorster, of the Rancho Murieta Association contacted Greg Miller, energy specialist for the Sacramento Municipal Utility District (SMUD), for assistance in stemming the Association’s growing energy usage. The Association had previously worked with SMUD to improve lighting efficiencies in the public areas and pumping for the numerous fountains. When the Association needed to take a look at the existing HVAC systems, they again looked to SMUD for assistance.
There was a 31-ton chiller, which had been in place for over 30 years. Zoning was clearly with this unit and proper heating and cooling levels were no longer being maintained. Comfort levels for the varied uses, such as the office, meeting room and childcare areas, were not being met. There was no gas service available to these facilities and initial review indicated a good application of heat pumps. Site analysis indicated that granite bedrock would preclude the use of a deep well ground source heat pump system and space precluded a horizontal loop system. It appeared that air source units would be the only answer, but luckily there was a lake owned by the Association nearby. After trenching 450 feet and insulating refrigerant running lines, the four heat transfer exchange coils were weighted to sink into the lake.
The total costs for the 8–15 SEER water source systems were only slightly higher than for an air source system while the efficiency proved to be considerably higher. Cooler water temperature contributes to a higher efficiency system through greater opportunity for heat exchange. A replacement chiller would have been significantly more expensive. The total expenditure of the installation was $39,000. SMUD provided efficiency incentives of $4,800 for savings of 32kW, 68,571 kWh and $5,800 annually. This system will pay for itself in just under seven years.
The Association has found that comfort levels to all of the varied zones were dramatically improved. Office staff no longer had to wear sweaters to survive the cold from the chiller. Also, safety and reliability were a big consideration in this improvement. Finally, the Association members (residential property owners) were aware that this was a high technology installation and were proud to have this as part of their community.
However, there were several obstacles along the efficiency path that were successfully overcome. Both the Association and residents raised concerns regarding the effect on the fish of the temperature change due to heating exchange coils being placed in the lake. Analysis showed that the size of this system and the related heat exchange loops would not change the temperature enough to have an effect on the fish population.
The Association has committed itself to future energy efficiency upgrades and will continue to evaluate the available options and make sure to see the big picture. While heat pumps were clearly the answer for this facility, research into the most efficient technologies and being open to a creative approach has given them an installation to be proud of.