# /energystar/products/most_efficient

`POST /api/energystar/products/most_efficient`

Price: 20 credits

Read an ENERGY STAR Most Efficient list — the annual shortlist of the best-performing certified models in a category, a stricter bar than ENERGY STAR certification itself. Returns the same full certification record as the product search, and takes the same brand, model number, market, free-text, exact-match and numeric-bound filters over the category's measured columns.

## How to use it

Most Efficient is a separate, stricter designation than ENERGY STAR certification, so this is not the same as filtering the whole category — use it when the question is about the best models rather than the qualifying ones. Its category list is shorter than the certification categories and the names differ: clothes_washers here covers residential washers only, and the heat-pump lists split by duct type. The lists are re-cut each year, so a category can be empty between cycles, which answers 412 rather than signalling a problem; energystar/product_types reports the current size of each. Column names for `filters`, `min_values`, `max_values` and `sort` are the underlying category's.

## Parameters

- `access-token` (string, required)

## Request body

- `timeout` (integer) — Max scrapping execution timeout (in seconds) (default: 300; min: 20; max: 1500)
- `product_category` (string, required) — Category whose Most Efficient list to read (one of: "air_source_heat_pumps", "ceiling_fans", "clothes_dryers", "clothes_washers", "dehumidifiers", "dishwashers", "displays", "ducted_heat_pumps", "geothermal_heat_pumps", "mini_split_heat_pumps", "residential_freezers", "residential_refrigerators", "room_air_cleaners", "room_air_conditioners", "ventilating_fans"; examples: "residential_refrigerators", "clothes_washers", "air_source_heat_pumps")
- `brand` (string, nullable) — Brand name, matched exactly (minLength: 1)
- `model_number` (string, nullable) — Model number, matched exactly (minLength: 1)
- `text` (string, nullable) — Free-text search across every column of the list (minLength: 1)
- `market` (string, nullable) — Keep models certified for this market (one of: "United States", "Canada", "Taiwan", "Japan", "Switzerland", "Europe", "Australia", "New Zealand")
- `filters` (object, nullable) — Exact-match filters on any column of the underlying category, keyed by the programme's own column name
  - `*` (string)
- `min_values` (object, nullable) — Lower bounds on numeric columns of the category
  - `*` (number)
- `max_values` (object, nullable) — Upper bounds on numeric columns of the category
  - `*` (number)
- `sort` (string, nullable) — Column to order by. Unset orders by product id (minLength: 1)
- `order` (string) — Direction for sort (default: "ASC"; one of: "ASC", "DESC")
- `count` (integer, required) — Max number of results to return (min: 1; max: 150000)

## Response

### 200 — Successful Response

- `@type` (string) (default: "EnergystarProduct")
- `id` (string, required)
- `product_category` (string, nullable)
- `product_type` (string, nullable)
- `dataset_id` (string, nullable)
- `dataset_name` (string, nullable)
- `brand` (string, nullable)
- `model_name` (string, nullable)
- `model_number` (string, nullable)
- `energy_star_model_identifier` (string, nullable)
- `energy_star_partner` (string, nullable)
- `additional_model_information` (string, nullable)
- `upc` (string, nullable)
- `markets` (array) (default: [])
- `is_most_efficient` (boolean, nullable)
- `available_on_market_date` (string, nullable)
- `qualified_date` (string, nullable)
- `certified_date` (string, nullable)
- `attributes` (object) (default: {})

## Errors

### 422 — Validation Error

A column name the underlying category does not have.

What to do: Check the fields against this schema. A URN with the wrong prefix is the most common cause.

- `detail` (array)
  - `loc` (array, required)
  - `msg` (string, required)
  - `type` (string, required)
  - `input` (any)
  - `ctx` (object)

### 408

The request ran past its time limit

What to do: Raise `timeout` in the request body, up to the maximum this endpoint documents. Lowering `count` or turning off the `with_*` flags also helps, because less work finishes sooner.

### 412

That Most Efficient list is empty for the current cycle, or nothing in it matched the filters.

What to do: Retrying will not help: either the entity does not exist, or the input points at a different one.

### 429

Too many requests: a rate limit or a usage window is exhausted

What to do: When the response carries an X-Retry-After header, wait that many seconds and retry: the same number is in the body as `detail.retry_after`, and the limit clears once that window passes. The message in the body names the limit that was hit.

### 500

Something broke on our side

What to do: Retrying will not help. If it keeps happening, send us the X-Request-ID from the response headers.

### 529

Rate limit reached, or the endpoint is overloaded

What to do: Wait at least 30 seconds, then retry.

## Response envelope

Success: Array of objects (may be empty if no results)

Error: Error may coexist with partial results if it occurs mid-execution. Check X-Error header and status code.

Every response carries these headers:

- `X-Error` — Error message text (present only on error)
- `X-Request-ID` — Unique request identifier
- `X-Execution-Time` — Execution time in seconds
- `X-Result-Count` — How many records the body carries. 0 means an empty result, which is a normal answer and not by itself an error. A non-zero count can come back together with X-Error when the failure happened partway through — read this header and X-Error independently.
- `X-Total-Available-Results` — How many records exist for this query, when the endpoint can say. On a `dry_run` request this is the answer and the body is empty. It saturates: the endpoint's documented maximum means 'at least that many', any smaller number is exact.
- `X-Warning` — Present when the request body carried keys this endpoint does not document. They were ignored, so any filter you meant to apply through them did not apply. Check the spelling against this schema and retry.
- `X-Retry-After` — Seconds to wait before retrying. Present only on 429.