HRV systems or heat recovery ventilators are unique machines that allow outdoor air to enter your home as if you opened a window. However, instead of wasting precious heating or cooling power that comes from your heater or AC, an HRV system brings the fresh, outdoor air to comfortable indoor temperatures. You get all of the benefits of an open window and fresh air while minimizing the heat or conditioned air loss.
ERV systems, or energy recovery ventilators, are practically the same except they humidify and dehumidify the outdoor air as well. This is great for our climate where humidity can also be a problem when your indoor air feels stuffy.
The CDC recommends introducing outside air into a home to create a healthy environment. HVRs and ERVs can help serve this purpose.