What is Apex Heat?
Apex Heat is a Finnish software company founded in 2021. Its product, Apex Heat App, is browser-based calculation software that energy consultants and engineering firms use to produce building energy audits, heating system comparisons, energy performance certificates and energy grant calculations. The calculation is built on building register data, hourly weather and energy price data, and the Finnish building regulations. Users include A-Insinöörit, AFRY, FCG, Retta, Sustera and Sweco.
9/18/2026
What does Apex Heat do?
Apex Heat develops calculation software for energy professionals and property owners, with which a building's energy projects are calculated from start to finish: replacing the heating system, adding insulation, ventilation heat recovery and solar power. A consultant enters the building's address, the software fetches the register data and calculates the alternative measures. The output is, for example, a report, an energy performance certificate or an energy grant calculation.
The software's user is typically an engineer or another energy professional who uses these calculations to serve building and property owners. Large property owners and property managers are also served by Apex Heat directly.
In a portfolio analysis the same calculation runs for hundreds or thousands of buildings at once. For Espoon Asunnot, a stock of more than 1,200 buildings was calculated. Read the Espoon Asunnot case.
For business partners Apex Heat also offers customised calculation, custom report templates and APIs through which the calculation is integrated into the partner's own services.
Who is Apex Heat for?
Apex Heat App is intended for energy consultants and engineers who serve property owners of all kinds in energy-related projects and prepare, among other things, assessments, reports, recommendations, plans and certificates for building owners.
Users include engineering and consulting firms, property management companies, energy utilities, real estate investors and managers, and cities.
What does Apex Heat App calculate?
For a single building, a property or an entire building portfolio the software calculates:
- Heating system comparison: ground-source heat pump, air-to-water heat pump, exhaust-air heat pump, hybrid solutions and district heating alternatives. Each gets an investment cost, annual savings, payback time, net present value and internal rate of return.
- Borehole sizing: how many boreholes fit on the lot, how deep they need to be and what drilling costs.
- Energy efficiency measures: windows, doors, walls, roof, ground floor and ventilation heat recovery.
- Solar power: a suitable system size, yield and profitability based on hourly consumption and irradiation.
- Energy performance certificate: the E-number and energy class in the current state and in every measure scenario, plus submission of the official certificate to the ARA certificate register.
- Energy grant: eligibility and amount of the residential energy grant.
- Emissions and pathways: carbon dioxide emissions per fuel and per district heating network, CRREM decarbonisation pathways and an EU taxonomy assessment.
What is the calculation based on?
The calculation is based on the building's register data, the building regulations' U-values for its construction year, local hourly weather data, and electricity spot prices, distribution tariffs and district heating companies' price lists. The energy performance certificate is calculated with the tables and reference weather set by the Ministry of the Environment decree.
Every assumption the software uses is shown to the user as an estimate, and the user can replace it with their own data, for example consumption read from invoices. Read why the calculation can be trusted.
What does Apex Heat not do?
Apex Heat does not sell heat pumps, does not carry out installations and does not do detailed design. It is independent of equipment suppliers and contractors, and its calculation is intended as the basis for decisions and for tendering.
The calculation does not replace measurement. Where no measured consumption exists for a building, the result is a modelled estimate whose purpose is to give the right order of magnitude and the right order of priority between measures.
Who is behind Apex Heat?
CEO Jussi Vimpari has worked as a postdoctoral researcher in real estate economics at Aalto University and is a visiting researcher there. The calculation methods build on his research. Tero Jaakkola leads product development and Lauri Nurmilaukas leads commercial operations. Meet the team.
How do I get started with Apex Heat?
Apex Heat App can be tested free of charge by contacting our team through the contact form. Go to the contact form.
Frequently asked questions about Apex Heat
Yes. Apex Heat was founded in Finland in 2021, and its calculation is built for the Finnish building stock, weather, energy prices and building regulations.
Basic building data comes from open registers and geographic data. If the building has a signed energy performance certificate, its data overrides the register data. The user can replace any value with their own.
Yes. The software can be tested free of charge by contacting Apex Heat.
Apex Heat App calculates the certificate according to the Ministry of the Environment decree and submits it to the ARA energy certificate register. The certificate is prepared and signed by a qualified certificate author who uses the software.
Yes. Apex Heat does not sell equipment or installations, and the result of the calculation does not depend on which solution it recommends.
Read more
Why can the calculation be trusted?
What the calculation is based on, how measured consumption is used and what the calculation does not know.
How easy is Apex Heat App to use?
What data is needed, how estimates work and what the software produces.
Does Apex Heat produce official energy performance certificates?
Software for producing certificates and for the scenarios that improve the energy class.
