Featured Article

Happy Equinox, St. Patrick's Day, and Super Moon!

Equinox House celebrates the spring equinox by bidding adieu to direct sunshine for the next 6 months as our “equinox overhang” protects us from excessive solar energy input while maintaining wonderful blue sky, non-glaring daylight throughout the summer. A beautiful super moon traversed our clerestory windows this week, bathing Equinox House in a wonderful silver light throughout the night.

Figure 1: St Patrick's Day dinner at Equinox House just before the spring equinox.

We had eleven for dinner on Tuesday, March 19, 2019 to celebrate St Patrick’s day and an eagerly awaited spring. The picture above shows Equinox House ready for guests along with a view of the final days of direct sunshine. The spring Equinox is an optimal time in our area to exclude direct sunshine from a home’s interior. Internal solar gain rapidly switches from being a beneficial heat gain to an undesirable air conditioning load. Blue sky (diffuse) light is more than sufficient with a 10% window area to floor area ratio to wonderfully light a home’s interior, while cutting excess summer solar heat gain by 85%! Ten square meters (about 90 square feet) of unprotected, solar facing windows with a SHGC (Solar Heat Gain Coefficient) of 0.5 transmits 5000 Watts of heat into a home (1.5 tons of cooling capacity)!

Figure 2: Air quality for eleven dinner guests after a day filled with cooking and cleaning is automatically managed with the CERV smart ventilation system.

During the day on March 19, cooking and cleaning preparations increase pollutant concentrations steadily until the CERV’s user-selected 850ppm threshold automatically triggered fresh air ventilation. Carbon dioxide generally “leads” pollutant levels in Equinox House because of our low VOC generation. In all-electric homes with judicious selection of no-VOC building materials and furnishings, and occupant activities that minimize VOC generation, CO2 will be the dominant pollutant because human metabolism generated VOCs tend to decay through natural reactions into CO2 and water. Cooking odors, as wonderful as they were on March 19, added to human VOCs, increasing VOCs above the human respiration generated CO2. By noontime, the CERV began fresh air ventilation as noted in Figure 2 with the green shading. Guests arrived by 5:30, and stayed until 10pm (we’re old, so that’s a late night for us). The CERV continued in fresh air mode until 6am the next morning when the CO2/VOC threshold dropped to 750ppm. An additional fresh air vent period was initiated later in the day on March 20 for a briefer period of time when pollutant levels again reached 850ppm.

CERVs came online nearly 5 years ago with our CERV-ICE (CERV-Intelligently Controlled Environment) platform. CERV-ICE provides CERV Community members free access to their archived data. CERV user data is not shared or sold to others. We introduced CERV Analytics two years ago to the CERV-ICE platform in order to better explain the meaning of our exposure to indoor pollutants.

Figure 3: Average VOC and CO2 levels are always low in Equinox House due to judicious choice of building materials and furnishings, occupant habits, and smart ventilation.
Figure 4: CERV smart ventilation keeps occupant pollutant exposure exceptionally low.

Figures 3 and 4 provide additional information on Equinox House’s air quality profile. In Figure 3, average weekly VOC and CO2 concentrations (in “ppm”, “parts per million”) are shown in relation to the “CERV Community” (all online CERV owners). Many CERV owners prefer an IAQ setpoint of 1000 to 1100ppm rather than the 850ppm we’ve selected for Equinox House. Figure 3 indicates that CERV Community CO2 average is 1000ppm, while CERV Community average VOC concentrations have been in the 600-700ppm range. Note that the CERV’s total VOC concentration units are based on a scale that is correlated to a human’s CO2 and VOC output rather than a true VOC concentration scale. We prefer this scale because it tells us whether a home’s VOC levels tend to be human dominated VOCs versus those VOCs added from other sources such as from furnishing and furniture offgassing, cleansers and chemicals, and other non-human sources. Figure 3 shows that Equinox House has a total VOC/CO2 ratio of 1.2. As VOC/CO2 ratio increases above 1.5, home occupants should investigate other potential sources of VOCs. It is important to realize that we humans are biochemical reactors, and we generate a broad range of chemicals as well as a wide range of output (not necessarily odorous; odor and chemical concentration are different characteristics). And, it is important to realize that not all VOCs are bad. Grandmother’s chicken noodle soup odors are healthy, medications delivered by nebulizer are essential, and the fragrance of a spring flower often produces a feeling of well-being.

Figure 4 shows Equinox House “pollutant-hours per day” exposure of VOCs and CO2. Similar to kilowatt-hours, a pollutant-hour is the integrate exposure to a pollutant concentration over a period of time. We define immersion of a human for 1 hour in 1000ppm of CO2 as one CO2 pollutant-hour. Similarly, we define immersion of a human for 1 hour in 1000ppm equivalent of total VOC for 1 hour as one VOC pollutant-hour. CO2 pollutant-hours and VOC pollutant-hours are vector combined (square root sum-of-the-squares) to form “total pollutant-hours”. The IAQ community is at an early stage of defining pollutant exposure, and as sensing technologies evolve (eg, VOC sensors that distinguish between chicken noodle soup aromas and formaldehyde), additional weighting or emphasis can be placed on different pollutants. Build Equinox’s pollutant exposure formulation anticipates and allows for this evolution to occur, as well as incorporation of other health and well being impacting factors such as particulates. Stay tuned!

Note that Figure 4 shows Equinox House to be 2 to 3 pollutant-hours per day. The green region (less than 25 pollutant-hours per day) is where we would like to see all homes. The yellow region in Figure 4 is the exposure range for homes ventilated with ASHRAE 62.2-2016 with occupancy based on 1 plus the number of bedrooms. The red region should be avoided, but unfortunately, we see too many homes (both leaky and sealed) with air quality in this range. Air quality is poor in leaky homes because where one lives and where the leaks occur are often different.

Figures 5 and 6: Good design and construction practices resulted in an economically optimized, zero-plus home with steady, comfortable indoor temperature and humidity.

Figures 5 and 6 display the comfort conditions in Equinox House on March 19 and 20. Proper design of home and comfort conditioning systems, coupled with the energy efficiency of smart ventilation and smart air distribution, result in high energy performance and a healthy indoor environment.

Visit our website to view these results and more than 4 years of online CERV data from Equinox House. Equinox House’s CERV unit is nearly 9 years old! Scroll down the home page to the “Take Control” section and click on the screen. Live Equinox House conditions will appear. Click on the control screen to make changes to current settings (we don’t enact your changes, but you’ll get a feel for how easy it is to control a CERV). Also, view “historical” and “analytics” information and observe the continual comfort and excellent IAQ in Equinox House, whether we’re in the middle of a polar vortex with -15F or experiencing our summer’s heat and humidity from Louisiana.

Interested in learning more about our IAQ Metrics? Check out our April 24th free Webinar, Indoor Air Quality Metrics: Avoid Living in a Home that Makes you Stupid, Sick, and Tired.

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August 27, 2019 Events – Earn Free CEUs with the Handling Humidity Webinar (Aug 29) 20190827
August 27, 2019 Featured Article – Handling Humidity Report Series 20190827
August 12, 2019 News – Listen to the Building HVAC Science Podcast, ft. Ty Newell! 20190812
July 29, 2019 Events – CERV2 Smart-er Ventilation Product Demo (Aug 27, 2019) 20190729
July 29, 2019 Featured Article – Poor Home Maintenance = Increased Health Risks 20190729
July 29, 2019 Tech – Say Hello to Our New Server! 20190729
June 19, 2019 Featured Article – Watch out for Cranky Heaters! 20190619
June 19, 2019 Events – Free CEU Webinar: Smart Ventilation & Air Distribution (July 10) 20190619
June 19, 2019 Spotlight – Marrakech Express! CERV2 Heading to Africa! 20190619
May 13, 2019 Featured Article – Taylor Home CERV Testimonial 20190513
May 13, 2019 Events – 7 Steps for Designing an Economical Net Zero Home (Video + PDF) 20190513
May 13, 2019 Tech – AeroBarrier Demonstration 20190513
April 15, 2019 Events – Indoor Air Quality Metrics Free Webinar (Apr 24, 2019) 20190415
April 15, 2019 Featured Article – CERV2 Geo–Boost Release 20190415
April 15, 2019 Review – 2019 National Home Performance Conference 20190415
April 15, 2019 Tech – CERV2 Sketchup Model Now Available 20190415
March 28, 2019 News – Visit us at the Chicago 2019 National Home Performance Conference 20190328
March 28, 2019 Featured Article – Happy Equinox, St. Patrick’s Day, and Super Moon! 20190328
February 27, 2019 Events – Free CEU Webinar: Smart Ventilation & Air Distribution (Mar 12) 20190227
February 27, 2019 Featured Article – Smart Ventilation and Smart Air Distribution Reports 20190227
February 27, 2019 Spotlight – El Salvador NZEB Update 20190227
February 25, 2019 Events – CERV2 Smart-er Ventilation Product Demo (Video + PDF) 20190225
January 22, 2019 Events – Smart Ventilation & Smart Air Distribution Webinar (Video & PDF) 20190122
December 26, 2018 Spotlight – Progressive Canada 20181226
December 26, 2018 News – Happy Holidays from Build Equinox! 20181226
December 26, 2018 Review – CERV2 at Greenbuild 2018 20181226
November 26, 2018 News – CERV OEM Filter Store is OPEN!!! 20181126
November 19, 2018 News – Check Out Our Social Media! 20181119
October 24, 2018 Events – Free CEU Webinar: Duct Design & Performance (PDF Download) 20181024
October 24, 2018 Featured Article – CERV2 is UL Approved! 20181024
October 24, 2018 News – Stop by Our Booth at Greenbuild Chicago (Free Tickets!) 20181024
October 24, 2018 Spotlight – University of Illinois Students Visit Build Equinox 20181024
July 23, 2018 Featured Article – Happy 10th Birthday, CERV and Sunflower! 20180723
July 23, 2018 Spotlight – Good News from El Salvador! 20180723
June 22, 2018 Tech – Installing a Ductless Mini-split 20180622
June 22, 2018 Featured Article – Mini-split Mania! 20180622
April 30, 2018 News – Now offering on-demand webinars for CEUs! 20180430
April 30, 2018 Events – Free CEU Webinar! (May 2, 2018) 20180430
April 30, 2018 Featured Article – Ductology Part 2 20180430
February 19, 2018 Review – 2018 Better Buildings by Design Conference, Flu and Colds 20180219
February 19, 2018 Featured Article – Hot Water! 20180219
January 22, 2018 Events – Visit us at BuildingEnergy Boston! (March 7-9, Boston, MA) 20180122
January 22, 2018 Events – Efficiency Vermont Better Buildings by Design Conference (Feb 7-8) 20180122
January 22, 2018 Featured Article – Ductology (Part 1) 20180122
November 20, 2017 Featured Article – Heat Pump (Hybrid) Clothes Dryers are Coming! 20171120
October 31, 2017 Featured Article – CERV2 Measures IAQ at NAPHC & NAPHN 20171031
September 25, 2017 Featured Article – Introducing CERV2 20170925
August 21, 2017 Events – Free CEU Webinar! (Sep 27, 2017) 20170821
August 21, 2017 Featured Article – Quiz 20170821
July 27, 2017 Events – New IAQ Metrics Webinar (Video + PDF) 20170727
July 25, 2017 Featured Article – Endotoxins: Small But Very Significant 20170725
May 22, 2017 Events – Economical Net Zero Design Webinar (Video+PDF) 20170522
May 22, 2017 Featured Article – Styrax Japonicus 20170522
April 28, 2017 Events – 7 Steps for Designing an Economical Net Zero Home (May 25) 20170428
April 28, 2017 Featured Article – Engineering Net Zero Homes 20170428
March 20, 2017 Featured Article – Build Equinox Zero Plus Facility 20170320
February 14, 2017 Featured Article – February Flu 20170214
January 20, 2017 Events – HRV, ERV and Smart Vent Systems, Free CEU Webinar (Feb 15) 20170120
January 20, 2017 Events – NESEA IAQ Metrics Presentation (Mar 9, Boston, MA) 20170120
January 19, 2017 Featured Article – The Perfect Dust Storm 20170119
January 12, 2017 Events – Efficiency Vermont Better Buildings by Design Conference (Feb 1-2) 20170112
December 26, 2016 Featured Article – Happy Holidays from Build Equinox! 20161226
November 29, 2016 Featured Article – Geo-Boost 20161129
November 29, 2016 Spotlight – This Old Passive House 20161129
November 29, 2016 Review – House Music 20161129
October 28, 2016 Featured Article – Comparing ERV, HRV, and CERV 20161028
October 28, 2016 Spotlight – Net Zero Eco-House (Monticello, IL) 20161028
October 28, 2016 Spotlight – Forty Under 40 20161028
September 28, 2016 Events – Free CEU Webinar (Oct 5th): Why are new Indoor Air Quality metrics needed? 20160928
September 28, 2016 Review – 2016 North American Passive House Conference 20160928
September 28, 2016 Featured Article – New CERV-ICE IAQ Analytics Released! 20160928
September 28, 2016 Spotlight – CERVs in Passive Homes, pt. 2 20160928
August 18, 2016 Featured Article – Understanding the House as a System 20160818
August 18, 2016 Spotlight – CERVs in Passive Homes 20160818
August 18, 2016 Review – “What is IAQ?”, P. Ole Fanger 20160818
August 18, 2016 Tech – CERV CO2/VOC Library 20160818
July 19, 2016 Events – September North American Passive House Conference 20160719
July 18, 2016 News – CERV Website 20160718
July 18, 2016 Featured Article – VERMOD CERV Report Released 20160718
July 18, 2016 Review – LBNL report: “Houses are Dumb Without Smart Ventilation” 20160718
July 18, 2016 Spotlight – Professor P. Ole Fanger (1934-2006); IAQ and Comfort Pioneer 20160718
July 18, 2016 Tech Note – Airflow Calculation for Ventilation Systems 20160718
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