Calculator › Brewery › Methodology
Every formula, default and assumption behind the numbers — so your team can reproduce them and apply the same method consistently to any hot equipment.
For each item of hot (or cold) equipment the calculator returns six things: heat loss bare vs insulated (W and W/m), the percentage reduction, the insulated outer surface temperature (touch-safe check), the annual energy, money and CO₂ saved, and the payback period. It is a steady-state, one-dimensional model — the industry-standard basis for insulation sizing and energy audits.
Heat flows from the hot process, through the wall and any insulation, to the surrounding air by convection and radiation. At steady state the flow is the temperature difference divided by the total thermal resistance.
Q/L = hₒ · π · D · (T − Tₐ)Q/L = (T − Tₐ) / [ ln(r₂/r₁)/(2π·k) + 1/(hₒ·π·D₂) ]
q = (T − Tₐ) / ( t/k + 1/hₒ ) (W/m²)R_cond = (1/r₁ − 1/r₂) / (4π·k)Where T = process temperature, Tₐ = ambient air, D/r = diameters/radii (bare and outer), t = insulation thickness, k = insulation conductivity, and hₒ = the combined outer surface coefficient.
| Symbol | Meaning | Value used |
|---|---|---|
| ho | Combined outer-surface coefficient — convection + radiation in a single value (the combined-coefficient route allowed by ASTM C680), for still / lightly-moving indoor air. | ≈ 10 W/m²·K |
| Ta | Ambient air (indoor plant; editable) | 20 °C |
| Tsurf,bare | Bare metal surface temperature | ≈ process temperature |
| Insulated outer surface | Solved by conduction through a 50 mm mineral-wool lamella cover — typically lands ≈ 30–40 °C (touch-safe, ≤ 45 °C) | computed |
Standards basis: ISO 12241 / VDI 2055 / ASTM C680.
Why a single combined coefficient (ho ≈ 10 W/m²·K)? Surface loss = convection + radiation, and both depend on things that vary site-to-site: air movement / wind, and the surface itself — emissivity of oxidised or painted steel (ε ≈ 0.9), bright metal cladding (ε ≈ 0.1–0.2), and the larger effective area of corrugated / profiled surfaces (e.g. some metal expansion joints). Rather than demand all of those for a quick estimate, the calculator uses one combined coefficient ho ≈ 10 W/m²·K (the combined-coefficient route ASTM C680 allows) so every result stays reproducible and comparable. Radiation is therefore not modelled separately; for hot bare surfaces this is deliberately conservative (radiation rises with temperature). Need an exact figure for a specific site? We run an individual calculation on request — your real weather / wind, surface type and emissivity (corrugated metal, bright cladding or fabric covers). Contact us.
Two tiers. The quick calculator, the DN×temperature reference tables and the equipment pages all use the conservative still-air ho ≈ 10 above, so the same surface always gives the same number. The detailed brewery, boiler-house and HRSG studies use a site model — light ventilation (v ≈ 0.5 m/s) plus explicit radiation — so their figures sit a little higher than a quick still-air estimate for the same surface.
Conductivity rises with mean temperature; the calculator interpolates k at the mean of process and surface temperature. Indicative values for the removable mineral-wool systems modelled:
| Mean temp | Lamella mat (k, W/m·K) | Wired mat (k, W/m·K) |
|---|---|---|
| 50 °C | ≈ 0.040 | ≈ 0.043 |
| 100 °C | ≈ 0.048 | ≈ 0.052 |
| 200 °C | ≈ 0.066 | ≈ 0.072 |
| 300 °C | ≈ 0.090 | ≈ 0.099 |
The heat saved is bare loss minus insulated loss. That is fuel you no longer burn, so it is divided by the boiler/heater efficiency before costing it:
Energy saved (kWh/yr) = Heat saved (kW) × hours ÷ efficiencyMoney saved = Energy saved × energy priceCO₂ avoided = Energy saved × emission factor
Because the saving is on burner fuel it is a direct Scope 1 reduction and a measurable ISO 50001 energy-performance gain. CO₂ is also shown as everyday equivalents (≈ 4.6 t/car·yr, ≈ 21 kg/tree·yr) purely to make the figure tangible.
Payback (years) = Installed insulation cost ÷ Annual money savedInstalled cost is the only commercial input. As an indicative guide, removable modular insulation is typically in the order of €150–€350 per m² of covered surface, installed — it varies with size, temperature, fabric and quantity.
A bare DN50 (2″) steam line at 150 °C, 50 m long with 4 valves, loses ≈ 13 kW. Removable insulation cuts that by ≈ 82%, so ≈ 10.7 kW is saved.
| Step | Figure |
|---|---|
| Heat saved | ≈ 10.7 kW |
| Fuel saved (÷0.85, ×8000 h) | ≈ 100 MWh/yr |
| Money saved (@ €0.07/kWh) | ≈ €7,000/yr |
| CO₂ avoided (@ 0.20 kg/kWh) | ≈ 20 t/yr |
| Covered area ≈ 25 m² × ≈ €200/m² | ≈ €5,000 installed |
| Payback | ≈ 8–10 months |
Most hot-line projects pay back in 9–24 months; bare valves and flanges pay back fastest.
Every default is editable in the live calculator — these are only the starting points.
| Input | Default | Notes |
|---|---|---|
| Ambient air | 20 °C | Still indoor air |
| Operating hours | 8,000 h/yr | ≈ continuous |
| System efficiency | 0.85 | Fuel → delivered heat |
| Energy price | €0.07/kWh | Currency switchable (€/$/£) |
| Emission factor | 0.20 kg CO₂/kWh | Natural-gas order of magnitude |
| Insulation thickness | 50 mm | Typical removable system |
| Outer coefficient hₒ | 10 W/m²·K | Still air, conv + rad |
The physics never changes — only the geometry and which dimension you enter. Use this map to keep results consistent across a brewery (or any plant):
| Equipment | Geometry | Enter |
|---|---|---|
| Steam / condensate pipe | Cylinder | NPS/DN size, length |
| Valves, flanges, pumps | Cylinder (equiv. length) | Count → equivalent metres |
| Boiler shell, doors, headers | Flat / cylinder | Surface area (m²) |
| Hot-water / CIP tanks | Flat sides + spherical heads | Surface area (m²) |
| Heat exchangers | Cylinder / area | Shell area or diameter |
| Bottle washers, pasteurizers | Flat panels + area | Hot-panel surface area (m²) |
| Brew kettle / mash tun | Cylinder + heads | Diameter, height, area |
The public calculator should not force every asset into one generic pipe case. Use the closest profile below, then confirm the real dimensions during the quote or site study.
| Profile | Use for | First-pass input | Production route |
|---|---|---|---|
| DN50 / DN100 steam pipe | Steam and condensate lines | DN/NPS, length, surface temperature | Quick tier / DN tables |
| Valve / flange group | Valve bodies, flanges, strainers, removable access points | Count or measured external area | Quick tier, then CAD/takeoff for quote |
| Steam trap station | Trap assemblies and small high-loss fittings | Count, exposed area, operating hours | Quick tier |
| Boiler door / casing panel | Boiler doors, hot panels, manways, inspection covers | Surface area and temperature | Detailed study if access constraints matter |
| Steam header | Large boiler-house headers and manifolds | Diameter/length or measured area | Quick tier or boiler-house study |
| Tank / vessel wall | Hot-water tanks, process vessels, CIP tanks | Shell/head area and temperature | Quick tier; vessel geometry in detailed study |
| Heat exchanger shell | Shell-and-tube exchangers, separators, hot cylindrical bodies | Shell area or diameter/length | Quick tier with survey confirmation |
| HRSG expansion joint | HRSG joints, irregular high-temperature gas-path components | Measured external area, temperature, operating hours | Detailed HRSG route: v≈0.5 m/s + explicit radiation |
| Exhaust duct | Ductwork, exhaust boxes, large flat hot surfaces | Panel area, temperature, air movement | Detailed route when airflow/wind is material |
| Turbine / casing zone | High-temperature casing sections and removable access zones | Measured area and surface temperature | Detailed study with access segmentation |
| Autoclave / process door | Autoclaves, retorts, sterilisers and process doors | Door/shell area and cycle hours | Quick tier, confirmed by survey |
Profile choice is not a claim. It only selects the closest geometry and default starting values. Final project numbers must use measured area, surface temperature, operating hours, fuel/energy price and the correct quick or detailed calculation tier.
| From | To | Factor |
|---|---|---|
| 1 W/m | BTU/hr·ft | × 1.040 |
| 1 kW | BTU/hr | × 3,412 |
| 1 MWh | kWh | × 1,000 |
| °C → °F | ×9/5 + 32 |
Energy price and emission factor are user inputs. Where a monetary carbon value is shown it comes from the live Carbon Hub (EU ETS market reference / CBAM certificate price, with source and as-of date) — a heat-loss result is not a CBAM compliance calculation.
Spotted an error in a formula, default or factor? Email contact@inzonex.co.uk — we review every report against the cited standard and record the change in the log below.
| Version | Date | Change |
|---|---|---|
| v1.0 | 2026-06 | Initial published method — ASTM C680 / ISO 12241 steady-state 1-D; convection + radiation summed; k(T) mineral-wool interpolation; energy = heat ÷ system efficiency; € = fuel × price; CO₂ = fuel × emission factor; payback = installed cost ÷ annual saving. |
Open the calculator, enter your equipment, and read heat loss, savings, surface temperature and payback live.
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The ASTM C680 / ISO 12241 method is the calculation layer. Inzonex Modular Insulation is the removable product system used to reduce the measured losses on access-critical hot equipment.
See Inzonex Modular Insulation ->