My local section experiences harshly cold winters & brutally sizzling summers.
Over the course of the year, the temperature fluctuates from a low of around twenty degrees below zero to a high of about ninety, then during the cold weather, with the gas furnace blasting, the condo tends to get especially dry.
We have the opposite problem when both of us switched to cooling. The excess of moisture causes musty smells & mold & mildew growth. Because both of us switch between heating & a/c with little to no chop in-between, there’s certainly rarely an opportunity to open windows & welcome natural ventilation. It’s necessary to keep windows & doors shut tight. I’ve taken extra measures to seal the thermal envelope & minimize energy waste. This helps to reduce the workload of the gas furnace & a/c however also traps allergens inside. Dust, dander, pollen, VOCs, bacteria, viruses & all sorts of nasty pathogens get continually circulated by the heating or cooling system. Any contaminants concealed inside the air duct can truly become airborne & add to the problem. Poor indoor air conditions can be blamed for all sorts of health issues, everything from sneezing, coughing & respiratory infection to exacerbated symptoms of asthma & psoriasis can be consequences of the hygiene & health of the air. I researched all different types of air quality accessories, debating between air purification systems, UV lights, humidifiers & dehumidifiers. I eventually chose a heat recovery ventilator that operates 24/7, all year round, introducing fresh air & removing stale air. By using the outgoing air to preheat the incoming air, it lessens demands on the gas furnace. The ventilation system also helps out the a/c by reducing issues with humidity.