"Scientifically Proven to Be Compact" Certification

The "Proven Airtight" certification is awarded to a homebuilder whose measured homes have demonstrated excellent average airtightness during the year under review.

You can recognize a certified airtight home builder by this logo:

The Significance of Recognition

Good airtightness is a key factor in modern construction. It improves the quality of living, ensures controlled air exchange, and significantly reduces the risk of moisture damage and energy consumption. Good airtightness is the result of careful planning and precise execution, which directly reflects the building contractor’s commitment to quality.

By 2025, Vertia will have measured the thermal performance of a total of approximately 1,100 single-family homes, which corresponds to about 30 percent of the single-family homes built in Finland last year. The properties that received the 2026 “Research-Based Compact” certification represent the best of all measured sites. The certification was not achieved through isolated successes, but rather demonstrates a long-term, reproducible, and high-quality construction.

Criteria for the "Research-Based Compact 2026" designation:

Awarded annually to the homebuilder whose homes, as measured, have demonstrated excellent airtightness during the year under review, that is air leakage rate qE50, with an average of no more than 0.6
It may also be granted separately for specific content only, for example Ready to Move – Delivery Contents
The minimum requirement is 10 measured points, but even this must be representative a significant portion of the homebuilder’s total projects or deliveries of the relevant product
The assessment is based on density measurements conducted by Vertia during 2025