Leak detection for university estates

Why a campus network is metered rather than surveyed

A university estate is too large to survey building by building and too continuously occupied to test against zero. The workable approach is to divide the network into metered zones, watch each zone's overnight minimum, and investigate the zone whose minimum has moved.

Most universities already have some of this in place through an energy management system. The gap is usually not the meters but whether anyone looks at the overnight minimum rather than the monthly total.

The estate profile a survey has to work around

The characteristic university asset is the buried heating main. Direct-buried pre-insulated pipe fails at joints and where the insulation has been compromised, and the water it loses is hot, treated and expensive to replace.

• District heating mains in ducts or direct-buried, with make-up water metering that may or may not be logged
• A private cold water distribution network the university maintains itself past the incoming meter
• Halls of residence with repeated identical plumbing, so one design fault multiplies
• Research buildings whose water use is genuinely unpredictable and should not be assumed to be a leak

Where the loss usually is on a campus

Heating make-up is the loss that costs most and shows least. A sealed heating network should need almost no make-up water. A network taking make-up continuously is losing treated hot water somewhere underground, and the first evidence is usually the dosing record rather than a wet patch.

• District heating mains and their joints, particularly at duct entries and manholes
• Cold water distribution across the campus, especially where roads and car parks have been laid over old runs
• Halls of residence cisterns and shower valves in aggregate
• Cooling water and process connections in laboratories
• Irrigation to sports pitches and grounds

Zoning a campus and reading the overnight minimum

The sequence is: confirm what the existing sub-meters actually meter, log overnight minimum flow per zone for a week, rank the zones by change against their own history, then survey the worst zone acoustically or with tracer gas. Ground microphones and correlation do the final positioning.

On heating mains the technique differs. Thermal survey along the route finds the hot spot where the leak is warming the ground, and tracer gas confirms the position before anyone breaks a surface.

Access, permits and the safeguarding position

Universities mostly manage contractors through permit-to-work and a contractor induction rather than through a school-style safeguarding regime, but the safeguarding duty still applies where under-18s are on site, which includes many first-year students, summer schools and outreach programmes.

Practically, the controls that matter are confined space entry for ducts and chambers, hot works permits and isolation authority on heating networks.

Working around vacations that are not empty

Vacation periods are when intrusive work happens, but halls are frequently let for conferences and residential courses, and research buildings do not stop. Expect the usable window to be narrower than the academic calendar suggests.

Detection is non-disruptive and can be scheduled in term. Excavation on a campus road or a pedestrian route needs a traffic management plan and a longer lead time than the dig itself.

What it costs and how it is justified

On a campus network the business case is usually written in cubic metres rather than in repair cost. A measured overnight loss, converted at the university's own volumetric rate, gives an annualised figure that funds the repair on its own without any argument about condition.

Heating losses carry a second cost: the energy in the water. That makes a district heating leak substantially more expensive per cubic metre than a cold water leak of the same size.