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Unformatted text preview: Home The Archives The former home of the 100k Blog Passive House Ventilation Design by Chad Ludeman on January 20, 2010 18 comments in HVAC , Passive House We thought it would be a good idea to review our new ventilation strategy and design implemented in the recent Passive Project . The ventilation strategy in the 100K House was different than most typical houses and the Passive Project took things a step further. Well start with the outline: 1. Use a very efficient mechanical ventilation system (ERV or HRV >90% efficient) 2. Design an efficient duct run layout to maximize efficiency of your ventilation system 3. Eliminate all dedicated local exhaust systems ducted directly outside 4. Eliminate all dedicated appliance exhausts that are ducted directly outside High Efficiency Mechanical Ventilation (ERV or HRV) The Passive House standard requires that you install a ventilation system with > 75% efficiency and a low electric consumption of 0.45 Wh/m3. When we say ventilation system, we are talking about either a Heat Recovery Ventilator (HRV) or Energy Recovery Ventilator (ERV). HRVs exchange heat only while ERVs exchange both heat and humidity. A 75% efficient unit will be exchanging 75% of the heat from the indoor air with the cold air coming inside. The closer that figure is to 100%, the closer the fresh, incoming air will be to the existing indoor temperature. Efficient electrical consumption is basically referring to the type of motor used in the ventilator. European models typically are using the most efficient DC motors available, while unit made in the US will suck a bit more power. If you are shopping the globe, you have a couple of options for mechanical ventilation that meet the Passive House reqs. If you want to buy in the US, you have one choice The UltimateAir RecoupAerator . This bad boy comes in black, runs at 95% efficiency and sucks a paltry 40 Watts while delivering 70 cfm to your home (250W @ 200cfm). This is what we speced on 100K and continue to use in Passive and for all foreseeable projects in the future. We set it on its lowest setting which usually measures about 60cfm in each room vent and let it run 24/7/365. Simple. This unit also comes standard with a MERV 12 filter which gains us LEED points and keeps our clients air very clean. Lastly, it features an EconoCool feature that can be used during the summer to reduce cooling loads. Flick this switch on and the unit will recognize when the temp drops below 65 degrees F and automatically shut off the energy recovery and begin swooshing that cool night air directly into your bedroom. Maximize Efficiency with a Well Designed Duct Layout Now that weve got the correct ERV for our needs, we need to pay attention to how we run our ductwork to maximize efficiency. The ERV will suck out stale air from the home and deliver fresh air to rooms at the same time. Below is how our PHIUS consultants recommended that we locate our suckers and blowers (technical Postgreen terms):...
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