It might sound uneconomical, but letting cool fresh air into your home or office can do a world of good. Specifically, staying in artificially warm or cold spaces for a long period of time is not good for your skin, say the Chinese. For one reason, conditioned air tends to take moisture out of your skin. This same air is also pumping out of a machine for hours and hours… There’s nothing natural about the quality of conditioned air.
Perhaps even more importantly, closing all windows and doors leads to the continual breathing of air that has germs in it and can’t escape. Without proper ventilation, germs stay in the air and you have a greater chance of getting a bug!
If you prefer to keep the rooms airtight in winter, make sure you step outside regularly and breathe in the nice crisp air of winter.