# Home Energy Calculators – HVAC Sizing (Room AC BTU)

> Home Energy Calculators – HVAC Sizing (Room AC BTU) is a paid API for AI agents from home-energy-calc.x402tookit.com, paid per call via x402, $0.02/call, status unknown (last checked 2026-10-29).

Calculates the recommended room air-conditioner BTU/h and tons from floor area using the ENERGY STAR chart, and optionally checks whether a given piece of equipment is correctly sized for a calculated load.

## Facts

- Endpoint: GET https://home-energy-calc.x402tookit.com/hvac-sizing?utm_source=zero.xyz
- Price: $0.02/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-29
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/home-energy-calculators-hvac-sizing-room-ac-btu-25b071e0
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_H1jEXjLcQM5lVL5kk3Jdb

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability home-energy-calculators-hvac-sizing-room-ac-btu-25b071e0
```

Example prompt: What size room air conditioner do I need for a 250 square foot bedroom, and is a 10,000 BTU window unit the right fit if my calculated cooling load is 9,500 BTU/h?

## When to prefer this

Use this endpoint when you need a quick, standards-based room AC sizing estimate grounded in the ENERGY STAR BTU-per-square-foot chart, especially for rooms between 100 and 400 sq ft with standard 8-foot ceilings. It is the right choice when you also want to validate whether existing or planned equipment is correctly sized against a calculated load. Prefer the sibling /heat-loss endpoint first to get a calculated load, then pass that result here for a complete sizing check. Not suitable for whole-house or commercial HVAC sizing, or for rooms outside the 100–400 sq ft range.

## Known failure modes

- roomSqFt outside 100–400 ft² range returns a validation error (ENERGY STAR chart only covers that range)
- loadBtuH outside 1,000–600,000 BTU/h range rejected
- Missing required roomSqFt when sizing check is requested
- Invalid 'kind' enum value (must be 'cooling' or 'heating')
- Providing equipmentTons and equipmentBtuH together may cause ambiguity or conflict
- Network or payment failure returns HTTP 402 or 5xx

## How this service works

Room air-conditioner BTU from floor area (ENERGY STAR chart), tons, and an under- or over-sizing check against a load.

## Output

Returns the ENERGY STAR-recommended room AC capacity in BTU/h, tons, and approximate watts for the given floor area, along with the chart row data used. If equipment capacity and a load are provided, also returns a sizing verdict (e.g. correctly sized, oversized, undersized), a list of reasons, a human-readable summary, and any factors not checked.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [],
     "properties": {
      "kind": {
       "type": "string",
       "description": "cooling (default) or heating, for the check window"
      },
      "loadBtuH": {
       "type": "number",
       "description": "A calculated load in BTU/h (see /heat-loss), 1000 to 600000, to check equipment against"
      },
      "roomSqFt": {
       "type": "number",
       "description": "Room floor area in square feet, 100 to 400 (the range the ENERGY STAR chart covers; 8-foot ceilings)"
      },
      "equipmentBtuH": {
       "type": "number",
       "description": "Equipment capacity in BTU/h (with loadBtuH)"
      },
      "equipmentTons": {
       "type": "number",
       "description": "Or equipment capacity in tons of cooling (1 ton = 12,000 BTU/h)"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "properties": {
      "asOf": {
       "type": [
        "null",
        "string"
       ]
      },
      "source": {
       "type": [
        "null",
        "string"
       ]
      },
      "reasons": {
       "type": [
        "array",
        "null"
       ],
       "items": {
        "type": "string"
       }
      },
      "summary": {
       "type": [
        "null",
        "string"
       ]
      },
      "verdict": {
       "type": [
        "null",
        "string"
       ]
      },
      "degraded": {
       "type": [
        "boolean",
        "null"
       ]
      },
      "roomSqFt": {
       "type": [
        "null",
        "number"
       ]
      },
      "disclaimer": {
       "type": [
        "null",
        "string"
       ]
      },
      "notChecked": {
       "type": [
        "array",
        "null"
       ],
       "items": {
        "type": "string"
       }
      },
      "roomAcBtuH": {
       "type": [
        "null",
        "number"
       ]
      },
      "roomAcTons": {
       "type": [
        "null",
        "num
… (truncated)
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/home-energy-calculators-hvac-sizing-room-ac-btu-25b071e0/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from home-energy-calc.x402tookit.com](https://www.zero.xyz/host/home-energy-calc.x402tookit.com/llms.txt)