Computes a transparent planning estimate for space-heating demand
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.
Answeringour last check, 2026-09-24
1 of 1checks answered this week
1183 msmedian answer time
$0.004listed price per call
$0.004price it asked us
Paid test badge: not yet. The checks above are free: we call the tool without paying and read the payment request it sends back. The Verified badge needs paid calls whose answers match the promised output, and nobody can buy a badge.
Endpoint
POST https://solar.halowerk.com/building-heat-demand
| Category | Everything else |
|---|---|
| Provider host | solar.halowerk.com |
| Networks | eip155:8453 |
| Payment schemes | exact |
| Self-reported calls, 30 days | 1 from 1 payers (the provider's figure, not ours) |
Our checks, last 30 days
| Day | Result | HTTP | Asked | Time |
|---|---|---|---|---|
| 2026-09-24 | valid payment request | 402 | $0.004 | 1183 ms |
Example input (from the provider)
{
"body": {
"domestic_hot_water_kwh_year": 1800,
"envelope": [
{
"area_m2": 168,
"name": "external walls",
"u_value_w_m2k": 0.22
},
{
"area_m2": 118,
"name": "roof",
"u_value_w_m2k": 0.16
},
{
"area_m2": 92,
"name": "ground floor",
"u_value_w_m2k": 0.25
},
{
"area_m2": 31,
"name": "windows",
"u_value_w_m2k": 0.95
}
],
"heated_floor_area_m2": 145,
"heated_volume_m3": 365,
"lat": 52.52,
"lon": 13.405,
"max_station_distance_km": 70,
"profile": {
"heating_base_temp_c": 15,
"indoor_temp_c": 20,
"internal_gains_w": 350
},
"system_efficiency": 0.92,
"ventilation": {
"air_changes_per_hour": 0.45,
"heat_recovery_efficiency": 0.15
}
},
"bodyType": "json",
"method": "POST",
"type": "http"
}
Promised output schema (from the provider)
{
"$schema": "https://json-schema.org/draft/2020-12/schema",
"properties": {
"input": {
"additionalProperties": false,
"properties": {
"body": {
"additionalProperties": false,
"examples": [
{
"domestic_hot_water_kwh_year": 1800,
"envelope": [
{
"area_m2": 168,
"name": "external walls",
"u_value_w_m2k": 0.22
},
{
"area_m2": 118,
"name": "roof",
"u_value_w_m2k": 0.16
},
{
"area_m2": 92,
"name": "ground floor",
"u_value_w_m2k": 0.25
},
{
"area_m2": 31,
"name": "windows",
"u_value_w_m2k": 0.95
}
],
"heated_floor_area_m2": 145,
"heated_volume_m3": 365,
"lat": 52.52,
"lon": 13.405,
"max_station_distance_km": 70,
"profile": {
"heating_base_temp_c": 15,
"indoor_temp_c": 20,
"internal_gains_w": 350
},
"system_efficiency": 0.92,
"ventilation": {
"air_changes_per_hour": 0.45,
"heat_recovery_efficiency": 0.15
}
}
],
"properties": {
"domestic_hot_water_kwh_year": {
"default": 0,
"maximum": 1000000,
"minimum": 0,
"type": "number"
},
"envelope": {
"items": {
"additionalProperties": false,
"properties": {
"area_m2": {
"maximum": 100000,
"minimum": 0.1,
"type": "number"
},
"name": {
"maxLength": 80,
"minLength": 1,
"type": "string"
},
"u_value_w_m2k": {
"maximum": 8,
"minimum": 0.01,
"type": "number"
}
},
"required": [
"name",
"area_m2",
"u_value_w_m2k"
],
"type": "object"
},
"maxItems": 40,
"minItems": 1,
"type": "array"
},
"heated_floor_area_m2": {
"maximum": 100000,
"minimum": 5,
"type": "number"
},
"heated_volume_m3": {
"maximum": 1000000,
"minimum": 10,
"type": "number"
},
"lat": {
"description": "Latitude in Germany; the DWD normal dataset used here covers Germany.",
"maximum": 56,
"minimum": 47,
"type": "number"
},
"lon": {
"maximum": 16,
"minimum": 5,
"type": "number"
},
"max_station_distance_km": {
"default": 80,
"maximum": 200,
"minimum": 1,
"type": "number"
},
"profile": {
"additionalProperties": false,
"properties": {
"heating_base_temp_c": {
"default": 15,
"maximum": 25,
"minimum": 0,
"type": "number"
},
"indoor_temp_c": {
"default": 20,
"maximum": 30,
"minimum": 5,
"type": "number"
},
"internal_gains_w": {
"default": 0,
"maximum": 100000,
"minimum": 0,
"type": "number"
}
},
"type": "object"
},
"system_efficiency": {
"default": 1,
"maximum": 1.5,
"minimum": 0.5,
"type": "number"
},
"thermal_bridge_w_k": {
"default": 0,
"maximum": 100000,
"minimum": 0,
"type": "number"
},
"ventilation": {
"additionalProperties": false,
"properties": {
"air_changes_per_hour": {
"default": 0.5,
"maximum": 5,
"minimum": 0,
"type": "number"
},
"heat_recovery_efficiency": {
"default": 0,
"maximum": 0.95,
"minimum": 0,
"type": "number"
}
},
"type": "object"
}
},
"required": [
"lat",
"lon",
"heated_floor_area_m2",
"heated_volume_m3",
"envelope"
],
"type": "object"
},
"bodyType": {
"enum": [
"json",
"form-data",
"text"
],
"type": "string"
},
"method": {
"enum": [
"POST",
"PUT",
"PATCH"
],
"type": "string"
},
"type": {
"const": "http",
"type": "string"
}
},
"required": [
"type",
"method",
"bodyType",
"body"
],
"type": "object"
}
},
"required": [
"input"
],
"type": "object"
}