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Dismal Manor is tighter than I thought. When occupied with the windows closed, CO2 rises into the 1000-2000 range. This article surveys engineered ventilation for Dismal Manor.

QingPing Air Monitor Lite images courtesy of HomeKit Reviews.

The QingPing Air Monitor Lite has been here a couple of days. I had expected I would have a particulate problem. In reality, the house is sufficiently tight that it retains emissions from internal sources like breathing mammals and greyhound butts. What the trend curves are showing is that, with the house closed up, CO2 accumulates. Since Dismal Manor is small, this is detectable in the bedroom when all 3 of us are in the lounge. After the break, I review the findings and


  1. 2022-09-16 Original



A bit of back story

Your author is a former submariner. One of the things we have to do as submariners is to maintain a healthful atmosphere. On a submarine, that means being careful about the chemicals used aboard through the entire life cycle of the boat, banning aerosol cans, replacing the oxygen the crew uses, removing the carbon dioxide the crew produces, and removing hydrogen and carbon monoxide from various sources like the battery and things that get hot like frying supper.

Submarines have continuous air monitors and equipment to clean the atmosphere. We also take advantage of opportunities presented by crew drills to ventilate the ship.

Dismal Manor CO2

Dismal Manor is showing CO2 in the 1000-2000 ppm range. This is 0.1 to 0.2 percent. As CO2 approaches 1%, it begins to affect human comfort and human performance. At this level, opening a window is sufficient management in temperate climates. The Norfolk climate is tending toward hot-humid for summer months and temperate for winter months.

Here at Dismal Manor, we can just open a window (well in late September we can). This works well. With good cross-ventilation like I have today, CO2 will be below 1000 PPM in a couple of hours (getting it down is a mixing problem). In the summer, attempts to cross-ventilate would introduce humidity into the building that the air conditioning would need to remove.

Example QingPing App CO2 Trend Display

Dismal Manor

Dismal Manor is a 1955 hip-roof ranch that has been remodeled to update the bathrooms, add a pantry and utility closet in conditioned space, replace 1955 metal frame windows, replace the entrance doors, and update the mechanical equipment to 2006 standards.

Dismal Manor

In 2005, roofing, siding, and window replacement was completed. This work included adding of ridge vents and soffit venting.

In the process of doing the 2015 remodel, the bathroom exhaust fans were added. The contractor tried to avoid a roofer call by headering the two fans together (forbidden by code). And the installer didn’t get that right. The second intake was connected down stream of the one fan actually ducted up. So neither bath has working ventilation.

Ecobee energy retention evaluation

Dismal Manor has been blower door tested in the past. With an attic pull down access and a ventilated attic, the evaluation sucked. Without a blower door sucking on the place, it does pretty well when it comes to summer heat gain. The triple glazed argon-filled windows have something to do with this but the live oak and willow oak shade the house from solar heat gain in the summer.

Eventually, I may do some mitigation in the attic if I discover I have humidity issues up there. In 2021, I was nervously watching evening humidity approach 80% in the attic (Eve Weather monitors).

Implications for the HVAC Update

The primary goal of the coming HVAC update is to replace the obsolescent 2006 equipment on a planned basis but delaying until residential machine refrigerant choices have settled down. The second goal is to divorce from natural gas as equipment replacement becomes necessary. This means that a cold climate heat pump will replace the current dual fuel furnace plus heat pump.

Since my residential HVAC contractor has appropriate trades on staff, (duct work, roof jacks, etc), this is a good opportunity to install mitigating ventilation while taking advantage of it to manage CO2 in addition to bath odor and humidity.

Residential Ventilators

Residential ventilation in smaller homes is independent of the heating plant. In larger homes, it may be integrated with it. Dismal manor is about 1100 square feet or 120 square meters so it is reasonable to do independent heating and ventilation.

There are two types of residential equipment, exchange ventilators which use a single machine to bring in make up air and discharge exhaust air. Heat recovery ventilators are similar but have a mechanical heat recovery device that transfers energy from the warm side to the cool side. In summer they cool but don’t dehumidify the make up air. In winter, they warm it. Since such a device would run continuously, heat recovery is beneficial. Heat recovery ventilators are about a $1000 machine for a structure like Dismal Manor.

By davehamby

A modern Merlin, hell bent for glory, he shot the works and nothing worked.