Overview

• The 2025 Heizspiegel shows year-on-year cost increases: pellets up about 20%, gas up 15%, heat pumps up 5% and heating oil up 3%, based on an average 70 m² flat in a multi-family building.
• Early-October market checks report wood-pellet offers around €339 per tonne (Heizpellets24 on Oct. 7) and heating oil at roughly €0.89–€0.94 per liter, still below the 365‑day average in many quotes.
• Landlords must ensure minimum indoor temperatures under DIN 4701, with practice guiding activation after roughly three consecutive days below 12°C outdoors, and tenants can seek remedies if standards are not met.
• co2online estimates that about 90% of households could cut annual costs by around €400 through better thermostat settings, correct shock ventilation, reduced hot-water use and targeted technical upgrades.
• Guidance warns against underheating because cold, damp rooms raise risks of mold and frozen pipes, which can damage buildings and jeopardize tenant health.