Case study

Pompy.app: a heat load calculator with heat pump selection

Calculating heat demand takes data users often do not have, so forms get abandoned. For the Pompy.app portal we designed and built a heat load calculator: a short path with 3D visuals that ends with a result and a list of recommended heat pumps.

Live at pompy.app

steps from building data to the result

3D visualisations of the building and its systems

500

heat pumps the calculator selects models from

We designed and built a heat load calculator (OZC) for the Pompy.app portal. It simplifies one of the hardest stages of choosing a heat pump: turning building data into heat demand, and then into a choice of equipment.

Scope of work

Industry: E-commerce and retail
Product type: Product calculator and configurator
Market: HVAC / heat pumps
Year: 2024-2026

Technologies

Headless CMS
Kalkulatory i konfiguratory produktów
Product Design
Web

Key facts

Step-by-step process: building, external walls and roof, glazing, systems
A dedicated set of 3D visualisations of the building and its systems
Result: heat demand and a list of recommended heat pumps
Clickable prototype tested before launch
A journey designed with mobile devices in mind

We turned a difficult calculation into a short journey that ends with an answer to what's next.

Heat load calculator step with building data and a 3D house model

Goals

01
An approachable process
Collect data users don't usually know off the top of their head, in short steps with hints.
02
A reliable result
Structure the data so it can be used to match heating solutions accurately.
03
Easy on a phone
A short, predictable journey with a clear sense of progress and the option to correct data.

Process

Discover Define Develop Deliver

Data scope
Data scope
Defining what information about the building is needed for a reliable result.
Step structure
Step structure
Splitting the process into stages, each keeping the number of decisions to a minimum.
Language and hints
Language and hints
Field descriptions that help users understand what they're entering and how it affects the result.
3D visualisations
3D visualisations
Renders of the building's shape, storeys, walls, windows and system components.
Clickable prototype
Clickable prototype
Testing the step logic, question order and how the result is presented before development.
Development
Development
The calculator live on Pompy.app, connected to the equipment database.

Mobile steps of the heat load calculator with 3D visuals

Set of 3D visuals of the building and installations

What we delivered

A tool that takes users from input data to a specific choice they can understand.

Multi-step journey - successive steps cover the building, external walls and roof, glazing and systems.
3D visualisations - simplified, neutral renders that show which part of the building each step refers to.
Summary and result - an overview of the building data and the calculated heat demand.
Equipment recommendation - a list of heat pumps matched to the data and assumptions entered.
Clickable prototype - a test version we used to refine the journey before launch.

Challenge: data that users often do not have

A heat load calculation needs data that users often don't know, and they don't always understand why it matters. Language that's too technical, or too many fields in one place, ends with the form being abandoned.

At the same time, the result had to be structured enough to base an equipment choice on. The second challenge was ease of use on a phone: a short, predictable process with the option to go back and correct data.

In practice, decisions to buy a heat pump are often made on the basis of simplifications or incomplete information.

Solution: short steps, hints and 3D visuals

The calculator is a clear, multi-step journey. Each step asks only a few questions, and hints explain what the data being entered means.

3D visualisations help users see the parameters in practice: the number of storeys, a habitable attic or the specifics of the heating system. Their style is deliberately simplified, so they suit different building types and don't distract from the decision.

Prototype before development

In parallel, we built a clickable prototype. It let us test the step logic, the order of questions and how the result is presented, and spot where users might get stuck, before the final version of the tool was built.

Building summary and heat demand in the heat load calculator

Heating system comparison and recommended heat pump models

Results: from a calculation to a list of heat pumps

The calculator solves an information problem and a decision problem at once: it helps collect the right data and translates the result into specific equipment.

Users aren't left with just a number. They get a list of heat pumps matched to their building, which shortens the path from interest to choosing a solution. Thanks to working on a prototype, the journey was refined before launch.