The debate over how much insulation to use is an important one. There’s no clear-cut answer. It’s hard to say "Use this much in Climate Zone 4 and this much in Climate Zone 5" because there are multiple variables involved. Here are the main ones:
- Climate zone
- Type of heating and cooling system
- Fuel used for heating
- Utility costs
- Photovoltaic (solar electric) system costs
- Comfort
- Your interests and goals, such as utility bills and carbon footprint
Analyzing these aspects can help decide the optimal amount of insulation to use. At a certain point, it becomes wiser to stop with the insulation, and spend your money on stuff that will yield better results.
Read the entire article here: The Diminishing Returns of Adding Insulation