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Halowerk Building Heat Demand Estimator
x402
Halowerk Building Heat Demand Estimator is a paid API for AI agents from solar.halowerk.com, paid per call via x402, $0.004/call, status unknown (last checked 2026-09-14).
Computes a transparent planning estimate of annual and monthly space-heating demand for a building in Germany, combining envelope transmission losses, ventilation losses, DWD climate normals, internal gains, and optional DHW.
Price / call$0.004
Success—
StatusUnknown
How this service works
Computes a transparent planning estimate for space-heating demand. The method is not DIN, VDI, GEG or PHPP and must not be used as regulatory proof. It combines transmission heat loss from each envelope component, ventilation heat loss from heated volume and air changes, monthly heating degree days from the nearest DWD 1991-2020 temperature-normal station, stated internal gains and optional domestic hot water.
Output
Returns a month-by-month and annual heating demand breakdown in kWh, split into transmission losses (per envelope component), ventilation losses, and domestic hot water; includes the DWD climate station used, its distance, heating degree days per month, and total annual heating energy demand adjusted for system efficiency.
Example use cases
Sizing a heat pump for a new build
“I'm planning a new single-family house near Freiburg (lat 47.99, lon 7.85) with 350 m³ heated volume, 140 m² floor area — walls are 150 m² at U=0.25, roof 90 m² at U=0.15, windows 25 m² at U=1.1, floor 90 m² at U=0.3. Ventilation is 0.4 ACH with 75% heat recovery. Can you calculate the annual and monthly heating demand so I can size the heat pump correctly?”
Comparing insulation retrofit scenarios
“My Berlin apartment block (lat 52.5, lon 13.4) has 1200 m³ heated volume and 480 m² floor area. Current envelope: 600 m² walls at U=1.2, 250 m² roof at U=0.8, 80 m² windows at U=2.8, 250 m² floor at U=0.9, 0.6 ACH ventilation. What's the annual heating demand, and then recalculate after a retrofit to walls U=0.25, roof U=0.2, windows U=1.1 so I can compare the energy savings?”
Checking heating demand for energy certificate prep
“For a small office building near Cologne (lat 50.93, lon 6.96) with 800 m³ heated volume, 300 m² floor area, envelope: 400 m² facade at U=0.45, 200 m² roof at U=0.2, 100 m² glazing at U=1.5, 200 m² slab at U=0.35; internal gains of 5000 W, ventilation 1.2 ACH with 60% heat recovery — give me a monthly heating demand breakdown so I can prepare for an energy consultation.”
Technical details
Endpoint
POSThttps://solar.halowerk.com/building-heat-demandWhen to prefer
Choose this endpoint when you need a fast, transparent heating energy estimate for a building in Germany using actual DWD 1991–2020 climate normals, and you can supply envelope U-values and geometry. It is not a regulatory calculation (not DIN 4108, VDI, GEG, or PHPP-compliant) but is well-suited for early-stage design comparisons, retrofit scenario analysis, or sizing heating systems where a quick physics-based estimate is sufficient.
Side effects
- Coordinates outside Germany (lat 47–56, lon 5–16) → validation error, no DWD station available
- No DWD station within max_station_distance_km → error indicating nearest station is too far
- Envelope array empty or missing required fields (name, area_m2, u_value_w_m2k) → schema validation error
- heated_volume_m3 below minimum (10 m³) or above maximum → validation error
- u_value_w_m2k out of range (0.01–8) → validation error
- Payment not included or insufficient (requires $0.004 USDC via x402) → 402 Payment Required
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| lat | number | Latitude in Germany; the DWD normal dataset used here covers Germany. |
| lon | number | |
| profile | object | |
| envelope | array | |
| ventilation | object | |
| heated_volume_m3 | number | |
| system_efficiency | number | |
| thermal_bridge_w_k | number | |
| heated_floor_area_m2 | number | |
| max_station_distance_km | number | |
| domestic_hot_water_kwh_year | number |
Tags
x402
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