Not ready to invest in a whole-house filtration or purification system in Zimmerman? Still looking for a way to make the home in your air cleaner? Then, it might be time to upgrade your furnace filter. Often forgotten about until it turns black, this pleated piece of fabric more than pulls its weight. Without it, you’d be dooming your home’s HVAC filter to an early end. But what should you look for in a higher-efficiency filter? What’s the deal with these permanent ones you’ve heard about? We’ll explore that and more below.