Garland ISD Harris Hill Administration Building

Project Overview

An HVAC retrofit of the Garland Independent School District (ISD) Administration Building resulted in improved comfort, easier equipment maintenance, and lower energy consumption.

Highlights

Renovation
K-12, Education

Project Team

Owner – Garland ISD

Architect – Glenn Partners

Civil Engineer – RLG Consulting Engineers

Structural Engineer – Alpha Engineers

Roofing Consultant – Drytec

Project Details

Garland Independent School District (ISD) initiated a renovation of the HVAC systems in their Harris Hill Administration Building. The goal was to resolve complaints from the building owner and occupants, including inadequate cooling, poor maintenance access, and high energy costs.

The project site consisted of two buildings—a three-story office building and a two-story office building—connected by an enclosed walkway. The interior spaces included offices, conference rooms, the district’s main board room, a VIP office for the superintendent, and a cafeteria.

The existing HVAC system included:

Packaged variable air volume (VAV) rooftop units (RTUs) with electric heat
Fan-powered electric terminal units with electric heat
Single-zone RTUs with electric heat for designated spaces

The building’s utility bills consistently exceeded those of comparable facilities. To reduce energy consumption, the new HVAC design eliminated electric heat as a critical step toward improving efficiency.

Mechanical Design Overview for the Garland ISD Harris Hill Administration Building

The new design introduced a 4-pipe chilled water/hot water system. However, the owner emphasized the need to preserve as much occupied space as possible. This requirement posed a major design challenge, as the facility lacked mechanical rooms to house chillers, boilers, air handling units, and other auxiliary equipment.

After several site visits and detailed evaluations, the team developed a creative solution to the space constraints:

In the three-story building, the team repurposed a former server room with a raised floor. Although no longer in use, the room provided enough space to install three central station air handling units (AHUs)—one for each floor.
In the two-story building, the team converted part of the shipping and receiving area to house three more AHUs—two for the floors and one dedicated to the kitchen and cafeteria.

The team also constructed a new central plant and equipment yard on an open area of the property. The central plant features high-efficiency air-cooled chillers, condensing boilers, a variable primary heating water system, and a primary/secondary chilled water system. Underground piping connects the plant to both buildings.

To further improve performance, the team resized the equipment to provide sufficient redundancy for peak conditions while supporting efficient operation under low-load conditions. For the superintendent’s office, they added a supplemental split direct expansion (DX) system. This unit ties into the ductwork of the central VAV air handling system and operates with multiple 2-position motorized dampers. This setup maintains comfort in the superintendent suite during off-hours while reducing energy use by limiting HVAC operation to that space alone.

Energy Efficiency

Eliminating electric heating played a key role in reducing the building’s overall energy consumption. To further enhance efficiency, the team right-sized the chillers, preventing unnecessary energy use during low-load conditions. Additionally, all air handling units now feature air-side economizers, which allow the system to take advantage of free cooling whenever outdoor conditions permit.

The team also made lighting upgrades by replacing many of the building’s fluorescent fixtures with energy-efficient LEDs. Moreover, the facility team now actively monitors and optimizes energy performance using a building-wide energy management system (EMS). Together, these improvements deliver significant energy savings and support long-term sustainability goals.

Indoor Air Quality

To ensure compliance with current industry guidelines, the design follows the most recent version of ASHRAE Standard 62.1. Moreover, each air handling unit includes ultraviolet (UV) light arrays that actively clean and purify the air. In addition, the team installed airflow monitoring stations to continuously track the amount of outside air entering the system.

Furthermore, the UV light arrays feature radiometers that verify ongoing performance and ensure consistent effectiveness. To enhance indoor air quality even more, the team placed carbon dioxide (CO₂) sensors in high-occupancy areas. As a result, the system delivers on-demand ventilation, ensuring occupants receive fresh air precisely when and where it’s needed most.

Innovation

One of the most innovative aspects of this project involved solving space utilization challenges. Converting an existing building from roof-mounted mechanical systems to interior mechanical rooms—especially when none originally existed—posed a significant obstacle. However, the team tackled this challenge head-on and successfully devised creative solutions to make the most of the available space. By thinking strategically and collaborating closely, they transformed underutilized areas into fully functional mechanical rooms without sacrificing occupied space.

Operation and Maintenance

With the equipment now located inside the building, the facilities team is now able to service the equipment more easily, comfortably, and in any weather condition. The new design has much less mechanical equipment, making the overall maintenance less burdensome. The EMS helps the facilities team to identify zones in need of attention from a central station. Also, the EMS system can help the maintenance team more quickly identify the root cause of equipment operation issues.

Cost Effectiveness

Overall, energy usage dropped significantly particularly during heating season. In addition, because the team used existing spaces inside the buildings, the owner saved on costs as no new mechanical rooms had to be constructed to house the AHUs.

Environmental Impact

The main environmental impact of this design was selecting an energy-efficient design. In addition to the items already covered, the team selected condensing, low NOx, high-turndown gas boilers. For the two, 200T chillers, the team selected an air-cooled chiller to save water. Additionally, the majority of the existing systems utilized R22 refrigerant, and all these systems were replaced, which eliminated this refrigerant from the facility and utilized a more environmentally friendly refrigerant in the new air-cooled chillers.