---
title: "Design Conditions Endpoint"
method: GET
path: "/api/design-conditions"
tags: ["Stations and data"]
---

# Design Conditions Endpoint

`GET /api/design-conditions`

## Request

- Base URL: `https://epw.tools`
- URL: `https://epw.tools/api/design-conditions`
- Auth: none declared

Return cached ASHRAE design conditions for any lat/lon — no EPW generation required.

Response includes:
- ``dc_line``    : the raw DESIGN CONDITIONS header string (for EPW header injection)
- ``ddy_content``: full EnergyPlus .ddy file text
- ``station``    : metadata for the nearest reference station and distance to it
- ``exceedance_outlook``: how often these values are expected to be exceeded now and in 10 years,
  from the measured lag of published design values (backend/design_lag.py)

## Query parameters

- `lat` number, required: Latitude in decimal degrees
- `lon` number, required: Longitude in decimal degrees
- `edition` string: ASHRAE edition: 2025, 2021, 2017, 2013, 2009, 2005
- `location_name` string: Name to embed in the .ddy file (defaults to nearest station name)

## Response `200`

Successful Response

- unknown

## Other responses

- `422`: Validation Error

---

[API](https://skmtc.dev/epw/apis/epw-tools-api.md) · [All operations](https://skmtc.dev/epw/apis/epw-tools-api/llms.txt) · [OpenAPI document](https://skmtc.dev/epw/apis/epw-tools-api/revisions/e6b60fc7a6d7?raw)