Major upgrade to the HVAC systems at the ALFA Headquarters building in Montgomery, AL were recently completed. HHB Engineers served as the Mechanical Engineers for the project during the design and construction phase.
Building Area involved in Project: 350,000 square feet
Project Construction Cost: $3.4 million
Scope of Work:
the HQ building was constructed in multiple phases from 1956 to a renovation in 2005. This project focuses on replacing the pre-1992 air handling units, consolidating two heating systems (one steam, other 180-F hot water), upgrade antiquated pneumatic controls to DDC, and upgrade the chiller plant. The upgrades will increase the energy efficiencies of the systems and lower both the eletricity and natural gas usage for the facility. The following are highlights of the project:
- Building was occupied during normal work hours (7-5, 5 days a week). Majority of the construction occurred during weekday nights and during weekends. Mechanical (as General) contractor had crews working 40-hour shifts Monday-Friday for approximately 3 months. Additional crews were used for 12 week-end shut-downs. All air handling unit replacements and change-overs occurred starting at 6-PM on a Friday and completed by Monday morning.
- 12 new variable air volume systems replaced 15 multi-zone constant volume air handling units.
- Two systems were replaced with new roof-mounted air handling units and new flat oval supply duct installed parallel to the 1956 and 1967 ductwork with phased change-over to the new systems. One system used new vertical supply and return duct extended through existing stacked mechanical rooms, existing air handling units removed after supply duct with VAV’s were installed.
- Two boiler plants consolidated into new plant, with work starting July 2015 and completed by October 10, 2015. Plant consists of two high mass variable flow condensing boilers (2500 mbh each). All new heating coils designed for 140-F and system operated through winter 2015 operating at 120-F or less 90% of the time.
- Replacement of three R-22 screw-type 350-ton chillers with centrifugal type. Refurbishment of existing water-side economizer system including re-building heat exchanger and new valves. System had not been used since 1985 due to issue with chillers operating at lower condenser water temperatures. Variable speed drive added to existing primary chilled water pump.
- HHB’s Design included a detailed phasing plans with 21 specific work phase line items with description of time constraints, weather constraints (when required) and prerequisite work activities.
- Project completed on-time, in-budget with no design-related change orders.