Project Overview
The client, a well-known national retailer in San Francisco, has a store that is comprised of 3 buildings which comprise over 1,000,000 square feet. Half is the selling floor and the remainder of the space is consists of stock rooms and storage. The buildings range from 8 to 11 stories tall. Over 1000 employees work during a typical day. The store spends over $2,000,000 in electricity alone each year. Our client desired to reduce their utility budget.
The Solution
Abraxas Energy Consulting performed a brief energy study on the building that included both retrofit and retro-commissioning measures. Initially, a utility bill analysis revealed a building with no clear trend in energy use which can be an indicator of haphazard controls. Three days were spent onsite investigating the mechanical systems including lighting and HVAC systems, and the building controls. Several RCx measures were identified. A list of energy conservation measures was produced that could reduce energy usage and costs. In a detailed report the buildings’ energy using systems were explained, a list of energy efficiency measures were provided, with their associated savings, installation costs, and simple paybacks.
Results
Abraxas identified over $325,000 in both RCx and Retrofit Measures. Our team worked with PG&E to get over $150,000 in incentives for our client. The retro-commissioning portion of the project paid for itself in less than 6 months.
Several problems were found with the HVAC controls, specifically: economizers that were not working, air handlers running without control, variable air volume controls that were not working properly, and uncontrolled chilled water valves. Recommendations were made to install variable speed drives(VSDs) on multi-zone air handling units(AHUs), install VSDs on secondary chilled water loops, repair economizer controls, repair faulty VSDs, reconnect static pressure lines, repair/replace inoperable chilled water valves and connect AHUs to the Energy Management System.
Once the measures were identified data loggers were installed to measure pre-implementation temperatures and power. Energy savings were estimated using bin data simulations. Each Energy Conservation Measure was modeled assuming the prior measures were already implemented. The interval data that we collected was integrated into the bin simulations.
The client then had a contractor add controls, replace faulty actuators, install chilled water valves, repair/reprogram faulty controls and add variable speed drives to the identified air handlers, and post-installation savings were measured, and the results were presented to PG&E.
Benefits
Our client has reduced their energy cost by over $325,000 annually.