Reduce heat loss and running costs, and improve air quality with Heat Recovery Ventilation (HRV). This BLOG explores HRV and ERV ventilation systems. Homes built years ago were not designed for efficiency and so they leaked air everywhere. Modern homes with 6+ Star rating are much more air tight and require ventilation systems to keep a fresh feel inside without needing open windows in winter and summer. Air leaks and open windows can account for a quarter of your energy costs.