Energetický průkaz

The energetický průkaz (formally Průkaz energetické náročnosti budovy, PENB) rates how energy-efficient a building is. The grade is shown on a colored bar in property listings. A and B grades are new or insulated; F and G are older, uninsulated.

It matters more than people think. A flat with a G rating means you're going to pay significantly more for heating. For a 60 m² flat in Prague, the difference between a B-rated and a G-rated building can be 3,000+ CZK per month in winter heating costs.