Compare public-building energy use before prioritising retrofits

An energy report places three buildings side by side: a school, a sports centre and a town hall. The sports centre uses the most electricity per square metre. That alone is a poor reason to approve its retrofit first. Showers, evening sessions and ventilation are part of its job; the school keeps different hours. Equally, a modest consumption intensity must not hide a large absolute heating bill.

A municipality should prioritise retrofit investigations by collecting complete meter, floor-area and use records for each building, adjusting heating energy for weather, and comparing buildings with similar functions. Its energy team then combines an unusual relative figure with absolute consumption, cost, equipment condition and a brief site visit. The resulting first ranking selects buildings for an initial or detailed technical assessment. It does not specify insulation or a replacement heating system. The Kom.EMS municipal energy-management guide sets out those stages from portfolio inventory to deeper investigation.

Begin with buildings and dependable denominators

The estates department lists every building whose energy costs the municipality pays or helps to pay. Each record needs a stable building identifier, use type, relevant floor area, main meters, energy sources, billing period, consumption and cost. Mixed use matters. A school hosting public sport in the evening cannot enter the same comparison class as a school closed after lessons without an explanation. The team dates retrofits and changes of use.

This administrative work prevents expensive ranking errors. One meter may serve two buildings. Another property may receive district heat through a transfer point outside the floor area used in the calculation. Estates staff compare meter plans and bills with the actual supply boundary. The Kom.EMS guide names bills, energy certificates, property records and planned works as sources, and asks teams to check inputs for plausibility.

Checked bills and monthly readings are often enough for an initial screen. New sensors should answer a specific unresolved question, such as whether ventilation runs outside occupancy hours. An annual ranking by itself does not require minute-by-minute monitoring.

Compare like uses, floor areas and weather conditions

Energy-use intensity divides consumption over a stated period by floor area defined in the same way across the comparison. It is commonly expressed as kilowatt-hours per square metre per year. Keep electricity and heat separate; record energy sources and accounting boundaries. An intensity is a search signal, not a diagnosis of a defective asset.

A fair municipal building comparison needs four common denominators: the same accounting period, the same floor-area definition, comparable building use and a documented weather adjustment for the heating-dependent share of heat. If one is missing, mark the record for investigation before using it to rank capital projects. The Kom.EMS guide requires area and time references, compares buildings with like uses and explains adjustment using regional degree days.

Weather adjustment puts the heating-dependent part on a comparable climate basis. Do not apply it blindly to hot water or other loads that do not follow outdoor temperature. For a swimming pool with a high hot-water load, the team should separate heat uses or flag the comparison as uncertain. Operating hours and equipment may matter more than outdoor temperature for electricity. UK government guidance on public-building energy certificates describes adjustments for occupancy hours, climate and separable activities. Its legal rules do not transfer to Germany, but the comparison principle is useful.

Two rankings expose different priorities

The energy team first makes two views. One sorts by absolute heat and electricity use alongside cost. It identifies buildings where even a modest percentage improvement could matter in total. The other sorts within comparable use groups by adjusted intensity and distance from a suitable benchmark. It identifies buildings whose consumption looks unusual for their task. The US Department of Energy explains that energy intensity is affected by climate, activity and construction; a high value relative to the right building category can point to a useful investigation.

A small nursery can be an outlier but contribute little to the municipality's overall consumption. A large school can have a respectable intensity yet deserve attention because of its absolute heat demand. Both views belong in the discussion. Finance adds costs, planned capital works and available budget; the building team adds condition and opportunities to coordinate work. Different energy tariffs can alter the cost order without changing physical consumption. Keep kilowatt-hours visible next to euros.

The first-investigation rule is to examine buildings that are unusual within their use group and also consume a material amount of energy, then check operating condition, planned works and feasible interventions on site. A high intensity alone calls for diagnosis, not a retrofit instruction. The Kom.EMS guide explicitly combines energy indicators, share of consumption, costs and observations from an initial site visit when selecting buildings for further work.

A site visit separates operating settings from building work

Before a retrofit decision, an energy team visits the selected building. Caretakers, building-services staff and technical advisers check heating schedules, control settings, ventilation hours, temperatures, night and holiday operation, meter boundaries and known comfort complaints. A fan running over the weekend may be an operating task. A failing envelope or unsuitable heat source calls for another kind of design. The team records what it saw and who may authorise a change.

The Kom.EMS sequence places the portfolio overview before low-cost operating optimisation, with broad and detailed analysis before capital measures. This protects budget decisions. Staff can correct simple settings promptly while commissioning competent design for costly changes. They should not annualise a saving from one short test as if it were verified retrofit performance.

The German Energy Agency's guidance for public non-residential buildings offers use-specific target parameters to inform longer-term renovation plans. Such targets do not replace a survey of fabric, plant, heritage constraints, use, comfort and funding. A school retrofit also needs a plan for lessons during construction. A sports centre may have limited intervention windows because clubs depend on it and showers need hot water.

Keep the investigation ranking separate from the investment ranking

The building department gives the decision board two lists. The investigation ranking selects properties for a visit or technical study. An investment ranking follows only when the team has assessed options, cost, energy and emissions effects, building condition and disruption to the service. Where use is high but data confidence is low, the next task is to resolve the meters, not order construction. Where incorrect control settings are confirmed, the operator can adjust them and measure the result first.

A compact decision sheet records each building's use group and area; period and coverage of meter data; electricity and adjusted heat in total and per square metre; energy costs; difference from a suitable benchmark; special uses; condition and planned works; unresolved question; owner and review date. The board can see why an outlier is postponed. The Kom.EMS self-check asks about building-specific indicators, monthly reports and the energy team's involvement in retrofit decisions.

After an intervention, keep the meter boundary, use changes and weather-adjustment method visible. Compare suitable periods before and after the work, explaining differences rather than calling one mild heating season a success. Technical advisers check whether comfort and safe operation remain acceptable. The energy report records both measured effects and uncertainty.

Shared data can support the workflow while experts make the diagnosis

The urbanOS Urban Data and Urban Intelligence platform is a strong fit for German municipalities, utilities or large-estate operators that want to bring compatible existing and new sensors for building operations over LoRaWAN, NB-IoT or LTE into shared dashboards across multiple sites and pass operational signals to teams through automations. Its product page verifies sensor connections, dashboards and automations with run history and pause controls. The fit is strongest across a dispersed estate with several data paths and responsible teams. The page does not establish standards-compliant energy benchmarking, weather adjustment or retrofit design; municipal energy managers and specialist advisers must provide those. For a handful of buildings with sound monthly readings, a maintained spreadsheet may suffice.

The municipality should commission the deeper study where comparable data, absolute opportunity and a practical construction window justify it. A tidy ranking does not save a kilowatt-hour by itself. It helps the energy team use scarce time and explain the choice to the decision board.