Orange Unified School District: HVAC & refrigeration bid work guide

Historic flatland and hillside campuses side by side

Older flatland campuses

Older school buildings in a historic city were designed before mechanical cooling was assumed. Air conditioning was added later, often by hanging packaged equipment on the roof or on the wall of a building never designed for ducts. The result is odd duct routings, supply air that reaches some rooms better than others, and equipment located where it could be fit rather than where it works best. Replacing a unit in such a building is rarely a straight swap: curb height, roof framing, duct transitions and electrical capacity all need attention.

Hillside and canyon-edge campuses

Campuses on the hills have tiered pads, longer walking distances between buildings and roof access that depends on retaining walls and stairs. Delivery trucks and cranes need staging areas that may be limited. Wind is a design factor: rooftop units and their screens see more of it, and economizer hoods and exhaust caps on exposed roofs take a beating.

Historic buildings and what they mean for an equipment project

Some school buildings in older cities are considered historically significant. If a building is designated or considered eligible for historic status, exterior changes such as rooftop equipment visible from the street may need additional review, and districts commonly consult their architect on what can change. We do not know which buildings in this district carry any such designation; ask the district. What we can say is that early identification saves months.

How Orange Unified is likely to procure work

As in other California school districts, construction work is generally competitively bid above statutory thresholds, with informal solicitations below. Districts that maintain many older buildings often rely on repeating service arrangements as well, whether an on-call contract, a cooperative contract or job-order vehicle. Policies and thresholds are the district's to set and they change over time, so confirm current requirements with the agency.

The district's purchasing and facilities pages and board agendas are the places to look. When a project touches an older building, expect the bid package to include architect-prepared drawings and a DSA component. The project delivery and bidding guide explains how those documents are usually structured. For a neighboring district that shares part of this geography, see Tustin Unified and Placentia-Yorba Linda Unified.

When work can actually happen

Summer remains the main window. Older buildings add risk to that window: opening a ceiling or roof can reveal conditions nobody expected, and a surprise on June 20 can consume the schedule. We recommend a pre-construction investigation, with the district's cooperation, so that the surprises happen before the window opens rather than inside it.

Smoke and ash from regional wildfires can affect campus air quality in the fall. Some districts keep students indoors on poor-air days, which puts more load on ventilation and filtration. That is a reason to understand what filtration your existing units can handle before choosing filters.

Documents the district will expect

• DIR registration, prevailing wage and certified payroll.
• Insurance and bonds per the documents.
• Student-contact background clearance such as fingerprinting.
• DSA review where applicable, and possibly additional review for historic structures.
• Hazardous-materials survey review.
• Title 24 acceptance testing and refrigerant records.

Where scopes tend to appear

Older-building HVAC retrofits; rooftop packages on hillside gyms and multipurpose rooms; cafeteria refrigeration; ice machines; water heaters; and controls that bring different vintages of thermostat under a single schedule. In the older buildings, ventilation adequacy is a recurring topic, and so are filtration upgrades that older fans cannot support.

Matching the fix to the building

A district with this much range rewards a contractor who is comfortable saying 'we need to look first.' Quoting an older building from a nameplate alone is how scope gaps are born: the curb does not match, the electrical is undersized, the ductwork cannot take the new airflow. We would rather spend a day on the roof and in the ceiling space than discover the gap in July with a crane on site and a crew waiting.

On older and constrained buildings we spend more time on investigation, because that is where bids are won or lost. We measure airflow and static pressure before recommending a unit, check structural and electrical constraints, and photograph what we find. Documentation goes into the DaVinci Portal. If a unit's replacement looks premature, the second-opinion diagnostic gives a measured answer. See also the City of Orange service area.

Phasing work in a district with old and new side by side

In a district with long-lived buildings, large projects tend to be phased over several summers because funding, design review and construction capacity do not line up in one year. Phasing introduces its own mechanical hazards. A first-phase unit may be sized for the building as it will be after phase three; a temporary duct connection may be left in place longer than planned; a controls upgrade in one wing may leave the next wing on an incompatible system.

1. Define the end state first, then back into the phases, so early equipment is sized for the finished building.
2. Document every temporary condition and put an owner and a date on its removal.
3. Keep controls compatible across phases, or budget explicitly for the interface.
4. Record as-built conditions after each phase, not at the end of the program.

We prefer to work with architects and the district's project managers early on phasing, because the cheapest time to catch a conflict is before equipment is ordered.

Inputs a useful bid needs

• Drawings and any historic or hazardous-materials information.
• Roof access and crane staging notes for hillside sites.
• Architect or engineer contact for structural questions.
• Summer window dates and blackout periods.
• Filtration and ventilation expectations.

Call (714) 594-9194 or visit bid projects.