Poorly insulated rentals cost their tenants real money every winter, and the letter on the energy certificate is the shorthand for that. Two sides of the question matter to anyone considering such a lease: what the rating does to monthly bills, and what the rules now say about letting these homes at all.
Legal for now, but the ground is shifting under it. Since 2023, the energy label feeds directly into the WWS, the points system that sets the maximum legal rent for regulated housing — an E, F, or G label earns fewer points than an equivalent A/B/C home, which caps what a landlord can legally charge for it. From 1 January 2029, it goes further: rental homes still labeled E, F, or G will be barred from being (re-)let at all until upgraded to at least D, with some exemptions for monuments, temporary-use properties, and small detached homes like houseboats. Until then, letting an F or G home is legal, it just costs more to live in — poor insulation and older heating systems typically mean noticeably higher gas and heating bills, often several hundred euros a year more than a comparable well-insulated home, on top of whatever rent you're paying. If your landlord isn't already talking about renovation plans, it's a reasonable thing to raise, since 2029 isn't as far off as it sounds.