BUILDING ENERGY - Fall 2017 - 30

CASE STUDY: HEALTHY BUILDINGS

AIR QUALITY IN
YOUR BEDROOM:
NIGHTTIME CARBON
DIOXIDE LEVELS IN
THE BEDROOMS OF
22 VERMONT HOMES
BY BRIAN JUST

PEER REVIEWED BY
MIKE DUCLOS

W

hile indoor pollutants of concern
include particulates, volatile organic
compounds (VOCs), moisture, carbon
monoxide and radon, carbon dioxide
(CO2) - which is relatively simple and
inexpensive to test accurately - is often considered
a proxy for other harder-to-measure pollutants. It
has become a common indicator of indoor air quality
and is reliably produced in all homes when humans
and their pets breathe.
During the 2016-2017 heating season, we tested
the indoor air quality in the bedrooms of 22 northern
Vermont homes. The study took place from
November 2016 through April 2017 and consisted
of in-home assessments to measure each home's
airtightness, ventilation levels and master bedroom
and whole-home volume, followed by four days/
nights of measuring carbon dioxide (CO2) levels. This
testing occurred in the primary occupied bedroom
with all of the home's windows closed. Participants

FIGURE 1: CO 2 CONCENTRATIONS VS. TIME FOR 22 HOMES.
SHADED REGIONS CORRESPOND TO NIGHTTIME PERIODS OF
9PM-7AM; RED LINE INDICATES 1000 PPM THRESHOLD.

30 * BUILDINGENERGY VOL. 36 NO. 2 | FALL 2017

were asked to leave the bedroom door(s) open and
closed on alternating days and keep a log of irregular
events such as doors opening/closing and people
entering/leaving the room.
The CO2 concentration of 1000 parts per million
(ppm) is a commonly used benchmark for "passable"
indoor air quality and as a set point for commercial
demand-controlled ventilation systems. The homes
in the study spanned a wide range of size, age,
airtightness, heating system type and occupancy,1
and represent a reasonable spectrum of existing
homes in New England.
During testing, a CO2 probe-data logger2 was
placed in a draft free location approximately 3 feet
above the floor (sleeping height), a minimum of
3 feet from the nearest sleeping being and at least
1 foot from walls.
HOW DID THESE HOMES DO?
All homes exceeded CO2 concentrations of
1000 ppm on at least one of the four nights. Periods
when bedroom doors remained open had significantly
lower CO2 levels for the majority of homes, yet only
one of the 22 homes stayed below 1000 ppm on both
door-open nights. Door-closed nights were much
worse: 86 percent of homes (19 of 22) exceeded
2000 ppm - double the 1000 ppm threshold - on at
least one of the nights with the bedroom door closed
and 32 percent (seven of 22 homes) had CO2 levels
that rose above 3000 ppm. One home exceeded the
measuring equipment maximum range of 5500 ppm.
Full results are shown in Figure 1.
Some homes clearly performed worse than
others. In an attempt to establish cause-and-effect,
we investigated impacts of airtightness, heating
system type, occupant density in the bedroom and
ventilation system.3



BUILDING ENERGY - Fall 2017

Table of Contents for the Digital Edition of BUILDING ENERGY - Fall 2017

From the Executive Director: A strategic plan for emerging professionals.
From the Board Chair: Taking flight into new territory.
What is Strategic Electrification? Simply Put, It’s an Energy Transformation: A core pathway to deep carbon reduction.
Better Steam Heat: Generating steam system upgrades in New York City.
Going All the Way:What it will really take to achieve net zero energy in Burlington, VT.
Are You Forging the Weakest Link?: A deeper dive into how the quest for resilience alters the design process.
Air Quality in Your Bedroom: Nighttime Carbon Dioxide Levels in the Bedrooms of 22 Vermont Homes: Can occupants of leaky houses breathe easy in their sleep?
Inclusive Diversity Key to Sustainability: Opinion: Sustainability planning must embrace diversity.
BuildingEnergy Bottom Lines: An interview with Jonathan Orpin.
High Performance Walls: Discover an alternative to traditional insulation methods that can reach superior insulation performance with thinner walls.
SAF®– A Solar Faade to Stay?: A technical overview of the newest attachment systems in the low-energy construction market.
NESEA Green Pages: This premier resource for sustainability professionals in the Northeast and beyond is just a few pages away. To have your business listed in next year’s Green Pages and become a NESEA business member today, visit nesea.org/join.
Index to Advertisers
BUILDING ENERGY - Fall 2017 - Intro
BUILDING ENERGY - Fall 2017 - cover1
BUILDING ENERGY - Fall 2017 - cover2
BUILDING ENERGY - Fall 2017 - 3
BUILDING ENERGY - Fall 2017 - 4
BUILDING ENERGY - Fall 2017 - 5
BUILDING ENERGY - Fall 2017 - From the Executive Director: A strategic plan for emerging professionals.
BUILDING ENERGY - Fall 2017 - 7
BUILDING ENERGY - Fall 2017 - From the Board Chair: Taking flight into new territory.
BUILDING ENERGY - Fall 2017 - 9
BUILDING ENERGY - Fall 2017 - What is Strategic Electrification? Simply Put, It’s an Energy Transformation: A core pathway to deep carbon reduction.
BUILDING ENERGY - Fall 2017 - 11
BUILDING ENERGY - Fall 2017 - 12
BUILDING ENERGY - Fall 2017 - 13
BUILDING ENERGY - Fall 2017 - 14
BUILDING ENERGY - Fall 2017 - 15
BUILDING ENERGY - Fall 2017 - Better Steam Heat: Generating steam system upgrades in New York City.
BUILDING ENERGY - Fall 2017 - 17
BUILDING ENERGY - Fall 2017 - 18
BUILDING ENERGY - Fall 2017 - 19
BUILDING ENERGY - Fall 2017 - INSERT1
BUILDING ENERGY - Fall 2017 - INSERT2
BUILDING ENERGY - Fall 2017 - Going All the Way:What it will really take to achieve net zero energy in Burlington, VT.
BUILDING ENERGY - Fall 2017 - 21
BUILDING ENERGY - Fall 2017 - 22
BUILDING ENERGY - Fall 2017 - 23
BUILDING ENERGY - Fall 2017 - Are You Forging the Weakest Link?: A deeper dive into how the quest for resilience alters the design process.
BUILDING ENERGY - Fall 2017 - 25
BUILDING ENERGY - Fall 2017 - 26
BUILDING ENERGY - Fall 2017 - 27
BUILDING ENERGY - Fall 2017 - 28
BUILDING ENERGY - Fall 2017 - 29
BUILDING ENERGY - Fall 2017 - Air Quality in Your Bedroom: Nighttime Carbon Dioxide Levels in the Bedrooms of 22 Vermont Homes: Can occupants of leaky houses breathe easy in their sleep?
BUILDING ENERGY - Fall 2017 - 31
BUILDING ENERGY - Fall 2017 - 32
BUILDING ENERGY - Fall 2017 - 33
BUILDING ENERGY - Fall 2017 - Inclusive Diversity Key to Sustainability: Opinion: Sustainability planning must embrace diversity.
BUILDING ENERGY - Fall 2017 - 35
BUILDING ENERGY - Fall 2017 - BuildingEnergy Bottom Lines: An interview with Jonathan Orpin.
BUILDING ENERGY - Fall 2017 - 37
BUILDING ENERGY - Fall 2017 - High Performance Walls: Discover an alternative to traditional insulation methods that can reach superior insulation performance with thinner walls.
BUILDING ENERGY - Fall 2017 - 39
BUILDING ENERGY - Fall 2017 - 40
BUILDING ENERGY - Fall 2017 - 41
BUILDING ENERGY - Fall 2017 - SAF®– A Solar Faade to Stay?: A technical overview of the newest attachment systems in the low-energy construction market.
BUILDING ENERGY - Fall 2017 - 43
BUILDING ENERGY - Fall 2017 - 44
BUILDING ENERGY - Fall 2017 - 45
BUILDING ENERGY - Fall 2017 - 46
BUILDING ENERGY - Fall 2017 - 47
BUILDING ENERGY - Fall 2017 - NESEA Green Pages: This premier resource for sustainability professionals in the Northeast and beyond is just a few pages away. To have your business listed in next year’s Green Pages and become a NESEA business member today, visit nesea.org/join.
BUILDING ENERGY - Fall 2017 - 49
BUILDING ENERGY - Fall 2017 - 50
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BUILDING ENERGY - Fall 2017 - INSERT4
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BUILDING ENERGY - Fall 2017 - 75
BUILDING ENERGY - Fall 2017 - 76
BUILDING ENERGY - Fall 2017 - Index to Advertisers
BUILDING ENERGY - Fall 2017 - 78
BUILDING ENERGY - Fall 2017 - cover3
BUILDING ENERGY - Fall 2017 - cover4
BUILDING ENERGY - Fall 2017 - outsert1
BUILDING ENERGY - Fall 2017 - outsert2
BUILDING ENERGY - Fall 2017 - outsert3
BUILDING ENERGY - Fall 2017 - outsert4
BUILDING ENERGY - Fall 2017 - outsert5
BUILDING ENERGY - Fall 2017 - outsert6
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