The ENERGY STAR® program divides Canada into four geographic zones distinguished by the Letter A, B, C and D (see Fig. 1). By choosing windows that meet the ENERGY STAR® performance level for your region, you will reduce energy costs and through increased energy efficiency, provide improved comfort levels in your home year round.

Northern Window & Door products are designed and built right here in Thunder Bay to meet or exceed Zone C requirements.

• Zone D: > 8000 Heating Degree Days
• Zone C: > 5500 to <= 8000 Heating Degree Days
• Zone B: > 3500 to <= 5500 Heating Degree Days
• Zone A: <= 3500 Heating Degree Days