# Sustainability API v2 Delta

{% hint style="info" %}
This Delta variant builds on the [Sustainability API v2](/english/sustainability/sustainability-api-v2.md).\
For authentication, base endpoints and full documentation, see the main [Sustainability API v2](/english/sustainability/sustainability-api-v2.md) page.
{% endhint %}

## Introduction

The **Sustainability Delta API** from **Altum AI** complements the [Sustainability API v2](/english/sustainability/sustainability-api-v2.md) with an endpoint that directly calculates the effect of individual sustainability measures. You can see how each measure contributes to an improved energy label and what the financial impact will be.

This Delta variant helps you to:

* Define specific sustainability measures
* Analyse their impact on the energy label and savings
* Easily compare different sustainability scenarios

### What the Sustainability API v2 Delta adds

With the Delta variant, you can:

* Input a set of **desired sustainability measures**
* Calculate the **expected energy label** based on those measures
* Calculate the **investment** **required** per measure (€)
* Estimate the **expected annual savings** and CO₂ reduction
* See how each measure contributes to a **higher BENG2 score**
* Receive **annual and monthly savings** in euros on energy bills and ROI (%)
* Get an indication of the **impact on property value**

### Why this is useful

Instead of only analysing the current situation and calculating what is needed for improvement, this Delta approach allows you **to calculate directly from the desired measures.** This makes the process:

* **Faster:** no need to fully recalculate the current situation first
* **Focused:** compare scenarios directly
* **Practical:** see what each measure delivers in terms of performance and ROI


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# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.altum.ai/english/sustainability/sustainability-api-v2-delta.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.