Friday, June 10, 2011

The Energy Recovery Ventilator

With an ICF home you have such a tight building envelope you might have to add mechanical ventilation. This is actually a very good thing since indoor air quality is one of the main concerns with modern houses. Two such systems are the Heat Recovery Ventilation (HRV) and Energy Recovery Ventilation (ERV) systems.

The Recovery Ventilators are ventilation systems which provides fresh air and improved climate control, while also saving energy by reducing the heating (or cooling) requirements. It does this by employing a counter-flow heat exchanger between the inbound and outbound air flow.

A Heat Recovery Ventilator (HRV), as the name implies, recovers the heat energy in the exhaust air, and transfers it to fresh air as it enters the building.  An Energy Recovery Ventilator (ERV) is closely related, however an ERV also allows you to control the humidity level of the intake air, which is helpful in keeping out humidity on rainy days, and keep it in during Winter. Indoor humidity can be controlled with an ERV, and this comes at additional cost, but we suggest it is well worth it.

An ERV in the home would normally be set to come on for five minutes every hour, and best practice appears to be for it to come on whenever the kitchen light is on (humidity, cooking odors), whenever a bathroom light is on, and whenever carbon dioxide rises above a set level (having a party). This will ensure outdoor fresh air indoors all the time, without the loss of the energy it took to warm or cool the house, complimenting the main system. 

Intakes need only be in the kitchen and bathrooms, and outlets should be in most other rooms. Often an ERV comes with the option of a water coil, for supplemental heat or cool of the living space; it appears to be recommend that you either get this, or get an addon water coil with drip pan (for chilled water). Print this post

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