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Taylorville High School / Pretty Good House Status Update 4: Manual D (Duct Design)
Spotlight
Feb 28, 2024

Matt Blomquist and students continue making great progress despite some bitter cold and miserably wet weather.  The picture sequence below gives an idea of Matt’s recent class period activities. He has morning and afternoon student groups, plus a Monday evening class from the local community college. Matt begins each class discussing the day’s activities and objectives. The students disperse into smaller groups with Matt continually making the rounds, answering questions, and providing additional instruction.  Check out Matt’s Build_Learn_Teach Instagram site to see details of their current progress.

The house is rapidly taking shape and looks great!

Figure 1: Matt discusses activities and goals with the afternoon class.

Figure 2: Matt is showing students how to check and correct (very little correction needed) interior double stud wall framing.

Figure 3: Matt is on the ladder showing students how to level and shim attic hatch.

Figure 4: Matt is on the scaffolding showing students how to line up truss edges.

Figure 5: Architect Emily Mottram's PGH house design is becoming reality!

Economically Optimized Duct and Simplified Duct Design or, PGD (Pretty Good Duct)

Manual D is the name given to a formal computational duct design procedure. Unfortunately, Manual D does not provide an economically optimized duct design. We are going to do better than that by providing a duct design procedure that, in the spirit of the PGH movement, provides a PGD, a pretty good duct. That is, a method providing an economically optimized duct that minimizes duct installation cost and lifetime operating cost.

Duct design calculations are one of the most computationally complex analyses to perform for house design. We need to ensure that ducts are sized to deliver sufficient air to keep a room’s occupants healthy and productive, while simultaneously keeping a room’s occupants comfortable! Unfortunately, duct design is often one of those “little details” that are often taken for granted, with someone “winging” it or shooting from the hip. Once the wallcoverings go up, and insufficient flow occurs, the finger pointing begins.

In addition to ensuring that ducts are sized appropriately relative to a fan’s flow and pressure capabilities, economic optimization of duct sizing is important. Even if a fan is capable of delivering a desired flow, fan power can easily consume more power than the heat pump conditioning the air stream.

The above makes duct design seem impossible, but fortunately, it is not, and you can do it! Yes, consulting an engineer or experienced duct designer is advisable for complex systems with multiple levels of branching and fittings, but for most homes of reasonable size and number of zones, you can properly design the home’s ducting.

Table 1 shows duct air flow characteristics for air flows of typical interest to many of today’s high-performance homes. The table shows important flow characteristics (pressure drop, fan power, annual energy usage) and economic factors (duct installation cost, lifetime energy cost, and the sum of installation and energy cost, or lifecycle cost). The left side of the table shows input information such as duct diameter, duct length, air flow, fan efficiency, duct (house) lifetime, energy cost, and installation cost. Note that installation cost has two installation cost factors related to duct length, and a factor related to duct length and duct diameter.

Data under the shaded column headings are the spreadsheet’s output, including fan power, duct pressure drop, duct velocity, lifetime energy cost, installation cost, and lifecycle cost. For sure, duct installation cost varies quite a bit from one end of North America to another. These numbers may look low for your area, but $1600 (including materials) to install 50 feet of 10" to 12” diameter of insulated flex duct should not seem too far off for most regions. If an installer needs to cut and hack and weave and bend around several objects, perhaps a higher cost is justified.

Examining Table 1’s economic results, we see that when we add lifetime energy cost with installation cost for a “lifecycle cost”, an optimum occurs. The optimum, as in many systems, is a place where one or more factors become more dominant as another factor loses significance. In this case, as we increase duct diameter, lifetime energy cost becomes less significant than duct cost. The yellow bar in each sub-table shows the lifecycle cost optimum for 100cfm, 200cfm, and 400cfm of air flow. The optimum lifecycle cost is somewhat shallow, allowing for maybe +/-1” duct size variation without too significant of impact on energy and cost. But, notice the steep increases when one tries to reduce duct size too much. Fan power and energy cost rapidly increase as duct size decreases.

Another important characteristic to notice in Table 1 is duct velocity. Over a broad range of cost factors and air flows typical of insulated ducts for residences, an economically optimized duct system had an air velocity in the 300 to 400fpm (feet per minute) range! For more background, read our two reports on optimal duct design, and duct distribution.

Assuming 400fpm as a target for air velocity in duct design, lots of good things happen. First, your duct system will reasonably well economically optimized, that is a PGD.

Second, air flow will be quiet! Duct noise is related to the kinetic energy of air flow, which is proportional to the square of duct velocity. Yesterday’s 800 to 1000fpm rule-of-thumb for residences and offices (which often was pushed much greater than that), generates 4 or more times as much noise as a duct with 300 to 400fpm velocity.

Third, there is some squishiness with 300 to 400fpm duct velocity, allowing for times when elevated air flow is desired (eg,  kitchen venting or design day comfort conditioning capacity air flow) as well as the ability to increase airflow for future additions. Note that if a future expansion is anticipated during current construction, it is best to use the future air flow for duct design analyses.

Fourth, “fitting losses” and “velocity head losses” (changes of duct cross-section area) are very small in the 300 to 400fpm range, and can be neglected.

Our duct distribution report demonstrates the difference between solving the exact duct flow and pressure drop equations to a designing a duct system by assuming 300 to 400fpm duct velocity. The difference is negligible! Ducts with 300 to 400fpm velocity are simple to balance, too, because each register controls flow unlike pressure drop restricted duct systems in which balancing is like squeezing Jello.

Table 2 brings us full circle by providing a range of duct sizes typical of residence air flows for IAQ and comfort management. One table is for round duct and one is for square duct. The table provides all the information needed for fresh air flow needs, heating needs and cooling needs within a zone. Note that heating assumes 120F delivery air and cooling assumes 50F delivery air, typical of today’s heat pumps.

These results can be extended to rectangular ducts by keeping the cross-section area the same. That is, a 6”x6” duct and a 3”x12” duct have the same cross section area with same flow capabilities as shown in Table 2. For those of you with more in-depth duct design background, the correction factors that would typically be applied because the 3”x12” duct has more perimeter are not significant for 300 to 500fpm velocities. Time is better spent in the field ensuring a quality installation with smooth duct connection and sealed joints than adding decimal points to calculations.

Table 1: Sample duct calculations and economic analyses for a 50ft length of duct with 100, 200 and 400cfm air flow.

Table 2: Recommended air flow, heating, and cooling capacity for round and square ducts.

THS PGH Duct Sizing

Let’s apply the preceding section methodology to the THS PGH project. From our last article, we conducted “Manual J” analyses on four house zones we defined for the THS PGH. Based on air flow requirements for air quality and for comfort conditioning, Figures 6 and 7 show supply duct and return duct systems for the THS PGH project. With the home’s insulated and conditioned crawl space, we have easy access to run ducts in any way we like, which makes duct installation efficient and reduces installation cost.

Tables 3 and 4 are from the previous THS PGH article showing air flows to each zone, with varying levels of occupants in each zone, based on air quality, heating and cooling comfort. The first row in each table (“PGH smart”) is the whole house comfort conditioning result obtained from ZEROs simulation modeling. The successive rows show Manual J modeling for each zone using ZEROs. As discussed in the previous article, our zone modeling includes the movement of home residents into each room, along with their individual needs for air quality and comfort in those zones.

Cooling dominates air flow needs in the home, with approximately 560cfm of total air flow. Zone 1, the open living area requires 480cfm on a sunny design day with 4 occupants. For air quality, zone 1 requires 160cfm of fresh air flow based on Build Equinox’s healthy IAQ Standard, which is twice the air flow required today’s odor-based, inadequate ASHRAE 62.2 ventilation standard.

The master bedroom (Zone 4) may require as much as 220cfm on a sunny, design day cooling day when occupied by 2 people, with 80cfm required for maintaining excellent indoor air quality, and 150cfm required for design day heating on a cloudy day. The other two-bedroom zones, assumed with single occupancy, require less than 100cfm each on design day heating and cooling day extremes, and otherwise less air flow for comfort.

We note that fresh air needs vary with human metabolism. For sedentary activity (typical movement around a house), 40cfm of fresh air per person will keep the indoor environment at 800ppm of CO2. During sleep, metabolism is lowered, with fresh air needs dropping to 20 to 30cfm per person for maintaining 800ppm of CO2. Periods of exercise and physical exertion (cleaning, cooking) elevate fresh air needs by 2 or 3 times (80 to 120cfm per person). The CERV2 automatically detects these fresh air requirements as activities and occupancy vary, and adjusts fresh air ventilation accordingly.

Most of the time (more than 99% of the time), design day conditions are not occurring, reducing comfort ventilation needs. Fresh air needs, however, continue such that on a day with very little heating or cooling, the CERV2 continues to modulate fresh air as dictated by CO2 and VOC levels.

Based on the above considerations, Zone 2 and 3 can be supplied with 6” round or square ducts, providing 80 (round) to 100 (square) cfm of air flow with our recommended 400fpm to each bedroom zone. Note that there is enough “squishiness” for the CERV2 and ducted minisplit to move higher airflow to these rooms during extreme weather. There is no problem with using larger 8” ducts branches to these bedrooms.

The main living area (Zone 1) can use a 6-inch duct branch for 80 to 100cfm supply air, while the master bedroom (Zone 4) is shown with an 8” duct branch to meet design day comfort needs up to 220cfm. These duct branches are plenty large for supplying fresh air needs above and beyond assumed occupancies.

Note that Zone 1 requires nearly 500cfm during extreme weather when fully occupied. We will discuss the comfort conditioning system design in the next article, but for the present, note that a 1-ton ductless minisplit heat pump located in the main living area supplies up to 400cfm of comfort conditioning air flow, which when combined with air flow delivered by the CERV2/ducted minisplit unit, satisfies extreme weather comfort air flow. There are some other advantages to the ductless and ducted heat pump arrangement that we will discuss in the next article.

Two 8” supply duct trunks from the CERV2/ducted minisplit connecting zone duct branches are shown in Figure 6. During typical conditions, the CERV2 will be operating at 200cfm air flow with 100cfm directed to each trunk. As comfort conditioning capacity increases, the CERV2 automatically increases air flow to 400+cfm (200+cfm per trunk).

The CERV2 contributes the first line of comfort conditioning. As temperature deviates from a desired temperature setpoint, the CERV2 senses the increased comfort capacity need and initiates “Stage 1” heating or cooling (roughly 50% of the minisplit capacity, however, there are capacity modulations occurring within each Stage setting). If additional capacity is required, the CERV2 detects the additional need, adjusting fan speeds and moving to Stage 2 capacity.

Return ducts follow a similar strategy as the supply ducts. We recommend placing returns in all bathrooms (but not supplies), kitchens, laundry, and other moisture, odor, or non-occupied rooms (eg, crawl space, walk-in closets). By continuously drawing air into bathrooms, bathrooms dry out. Note that bathroom air should be as fresh as the air everywhere else in a home, and in CERV2 homes, it is.

Some air should flow through all spaces in a home whether or not occupied. For non-occupied spaces, air flow is generally a nominal amount (eg, a 2” or 3” duct opening) that keeps air fresh and avoids moisture buildup.

We show 6” branches from the two bathrooms and the kitchen connected to an 8” trunk returning to the CERV2 unit. Approximately half of the return airflow (100cfm) will follow this path during normal CERV2 ventilation and recirculation modes. The remaining 100cfm of return air to the CERV2 moves through the main living area to the laundry and mechanical room. Note that when bedrooms are unoccupied, fresh delivered to those rooms is delivered to occupants in the main living area. The CERV2’s whole house recirculation and filtration mode also ensures that all fresh air delivered to a home is efficiently used to benefit home occupants wherever they are located.

A heat pump water heater will be located in the mechanical room with the CERV2 unit, too. Return air into the mechanical room maintains room temperature conditions in the mechanical room, maintaining heat pump water heater efficiency and capacity at all times. We will discuss this aspect of system design in an upcoming article.

Next Time

Maintaining good air quality is more than simply blowing some air at a specified ventilation level into house and assuming air quality is good. Effective distribution is essential to ensure stale air is purged from a home.

THS PGH will have excellent air quality and will be very comfortable in all weather conditions. Follow our next article on IAQ and comfort conditioning system design to learn why!

Figure 6: THS PGH floorplan showing supply duct layout four zones. Also shown is a 1 ton ductless minisplit heat pump in the main living open living area (Zone 1) and a ducted 1 ton minisplit and ducted dehumidifier integrated and controlled by a CERV2 smart IAQ ventilation system.

Figure 7: Return duct layout for the THS PGH house showing two return trunks from the bathroom/kitchen and from the main living areas.

Table 3: Airflow required to deliver heating and cooling comfort conditioning capacity to each room. Today’s heat pumps deliver 120F air for heating, and 50F for cooling.

Table 4: Indoor air quality air flow levels required in each zone for maintaining 40 cfm per zone occupant.

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Jun 29, 2020 Events – Free New Webinar: Guidelines for Protecting Against COVID-19 (PDF + Slides) Tags: Health, Webinar 20200629
Jun 25, 2020 Featured Article – Designing a Thermally Massive Home/ASHRAE Solar ZEB Article 7 Tags: ASHRAE, Equinox House 20200625
Jun 25, 2020 Special Edition – Covid19 Status Report: We are at the Beginning of the Pandemic, Not the End Tags: Health 20200625
May 29, 2020 Spotlight – CERV Retrofit: New Lungs for a 101-Year-Old Home Tags: CERV, Renovation 20200529
May 29, 2020 Special Edition – Covid19 Status Report: Guidelines for Homes & Businesses Tags: Health 20200529
May 29, 2020 Featured Article – Ground Heat Transfer/ASHRAE Solar ZEB Article 6 Tags: ASHRAE, Equinox House 20200529
Apr 16, 2020 Events – Free CEU Webinar: Covid-19 Characteristics, Transmission, and Control (April 29th) Tags: Health, Webinar 20200416
Apr 16, 2020 Special Edition – Battling the Spread of Covid-19 Tags: Health, Report 20200416
Apr 16, 2020 Featured Article – Infiltration & Sealing/ASHRAE Solar ZEB Article 5 Tags: Energy Efficiency, Equinox House, Net Zero, Report 20200416
Apr 16, 2020 Spotlight – New Projects: 1930s CERV Retrofit & Mitsubishi Hyperheat Tags: CERV, Energy Efficiency, Heat Pump, Ventilation 20200416
Mar 13, 2020 Featured Article – Light and Delight/ASHRAE Solar ZEB Article 4 Tags: Comfort, Energy Efficiency, Equinox House, Solar 20200313
Mar 10, 2020 News – CERV Voted One of the Top 16 Coolest Things Made in Illinois! Tags: CERV 20200310
Mar 5, 2020 Special Edition – Fighting COVID-19 with Fresh Air Tags: Health, Indoor Air Quality, Report, Ventilation 20200305
Feb 24, 2020 Featured Article – Walls and Roof/ASHRAE Solar ZEB Article 3 Tags: Equinox House, Net Zero, Report, ZEROs 20200224
Feb 24, 2020 Tech – Magic-Box Mechanicals Tags: CERV, Comfort, Heat Pump, Ventilation 20200224
Feb 24, 2020 Events – Designing Exceptional Homes for Exceptional People Webinar (Video + PDF) Tags: Comfort, Energy Efficiency, Net Zero, Webinar, ZEROs 20200224
Jan 30, 2020 Events – Visit us (Booth 17) at Energy Design Expo in Duluth (2/25-26) Tags: CERV 20200130
Jan 14, 2020 Tech – Designing Exceptional Homes for Exceptional People Tags: Comfort, Ducting, Humidity, Indoor Air Quality, Report, Ventilation, ZEROs 20200114
Jan 14, 2020 Featured Article – Designing for Zero/ASHRAE Solar ZEB Article 2 Tags: Energy Efficiency, Equinox House, Net Zero, Report, Solar, ZEROs 20200114
Dec 19, 2019 Events – Free Webinar: Smart Ventilation & Air Distribution (Video+PDF) Tags: Ducting, Ventilation, Webinar 20191219
Dec 19, 2019 Events – CERV2 Smart-er Ventilation Product Demo (Video + PDF) Tags: CERV, Webinar 20191219
Dec 19, 2019 Spotlight – Acorn Glade: 2019 NAPHC Awardee! Tags: CERV, Net Zero, Passive House, Solar 20191219
Dec 16, 2019 Featured Article – Equinox Origins/ASHRAE Solar ZEB Article 1 Tags: Equinox House, Report 20191216
Nov 19, 2019 Events – Visit our booth at 2019 NAPHC in Washington DC! Tags: Passive House 20191119
Nov 19, 2019 Spotlight – Equinox House Turning 10! Tags: Equinox House 20191119
Nov 19, 2019 Featured Article – Handling Humidity Pt.4 Putting it All Together Tags: Humidity, Report, Ventilation, ZEROs 20191119
Oct 16, 2019 Events – Mechanical Systems for Passive Buildings (Chicago, Oct 16) Tags: CERV 20191016
Oct 16, 2019 Featured Article – Handling Humidity Pt.3 Methods for Managing Moisture Tags: Comfort, Humidity, Indoor Air Quality, Ventilation 20191016
Oct 16, 2019 Events – Free Webinar: Handling Humidity (Video + PDF) Tags: Comfort, Humidity, Indoor Air Quality, Ventilation, Webinar 20191016
Oct 16, 2019 Events – Free CEUs: Building Green & Beer at Founders Brewing (Oct 28) 20191016
Oct 16, 2019 Spotlight – Inter House Wins Solar Decathlon Africa!!! Tags: CERV, Net Zero, Solar 20191016
Sep 20, 2019 Featured Article – Handling Humidity Pt.2 Climate Moisture Variations Tags: Comfort, Humidity, Ventilation, ZEROs 20190920
Sep 20, 2019 News – Brand New Release: Colorfil VOC Absorbing Filters! Tags: CERV, Filters, Health, Indoor Air Quality, Ventilation 20190920
Sep 20, 2019 Tech – From CERV to CERVEZA: a Quest for Smart Beer Tags: CERV, Heat Pump 20190920
Aug 27, 2019 Events – Earn Free CEUs with the Handling Humidity Webinar (Aug 29) Tags: Comfort, Humidity, Ventilation, ZEROs 20190827
Aug 27, 2019 Featured Article – Handling Humidity Report Series Tags: Comfort, Humidity, Ventilation, ZEROs 20190827
Aug 12, 2019 News – Listen to the Building HVAC Science Podcast, ft. Ty Newell! Tags: CERV, Comfort, Health, Indoor Air Quality, Webinar 20190812
Jul 29, 2019 Events – CERV2 Smart-er Ventilation Product Demo (Aug 27, 2019) Tags: CERV, Heat Pump, Ventilation 20190729
Jul 29, 2019 Featured Article – Poor Home Maintenance = Increased Health Risks Tags: Comfort, Ducting, Energy Efficiency, Health, Humidity, Ventilation 20190729
Jul 29, 2019 Tech – Say Hello to Our New Server! 20190729
Jun 19, 2019 Featured Article – Watch out for Cranky Heaters! Tags: Energy Efficiency, Heat Pump 20190619
Jun 19, 2019 Events – Free CEU Webinar: Smart Ventilation & Air Distribution (July 10) Tags: CERV, Ducting, Energy Efficiency, Indoor Air Quality, Ventilation 20190619
Jun 19, 2019 Spotlight – Marrakech Express! CERV2 Heading to Africa! Tags: CERV, Net Zero, Solar 20190619
May 13, 2019 Featured Article – Taylor Home CERV Testimonial Tags: CERV, Comfort, Indoor Air Quality, Ventilation 20190513
May 13, 2019 Events – 7 Steps for Designing an Economical Net Zero Home (Video + PDF) Tags: Energy Efficiency, Net Zero, Solar, Ventilation, Water, Webinar, ZEROs 20190513
May 13, 2019 Tech – AeroBarrier Demonstration Tags: Energy Efficiency, Ventilation 20190513
Apr 15, 2019 Events – Indoor Air Quality Metrics Free Webinar (Apr 24, 2019) Tags: Comfort, Health, Indoor Air Quality 20190415
Apr 15, 2019 Featured Article – CERV2 Geo–Boost Tags: CERV, Energy Efficiency 20190415
Apr 15, 2019 Review – 2019 National Home Performance Conference Tags: Indoor Air Quality 20190415
Apr 15, 2019 Tech – CERV2 Sketchup Model Now Available Tags: CERV 20190415
Mar 28, 2019 News – Visit us at the Chicago 2019 National Home Performance Conference Tags: CERV 20190328
Mar 28, 2019 Featured Article – Happy Equinox, St. Patrick’s Day, and Super Moon! Tags: Equinox House 20190328
Feb 27, 2019 Events – Free CEU Webinar: Smart Ventilation & Air Distribution (Mar 12) Tags: CERV, Ducting, Energy Efficiency, Indoor Air Quality, Ventilation, Webinar 20190227
Feb 27, 2019 Featured Article – Smart Ventilation and Smart Air Distribution Reports Tags: CERV, Ducting, Energy Efficiency, Indoor Air Quality, Ventilation 20190227
Feb 27, 2019 Spotlight – El Salvador NZEB Update Tags: CERV, Net Zero, Solar 20190227
Feb 25, 2019 Events – CERV2 Smart-er Ventilation Product Demo (Video + PDF) Tags: CERV, Heat Pump, Indoor Air Quality, Ventilation, Webinar 20190225
Jan 22, 2019 Events – Smart Ventilation & Smart Air Distribution Webinar (Video & PDF) Tags: CERV, Ducting, Energy Efficiency, Indoor Air Quality, Ventilation, Webinar 20190122
Dec 26, 2018 Spotlight – Progressive Canada Tags: CERV, Net Zero, Passive House, Solar 20181226
Dec 26, 2018 News – Happy Holidays from Build Equinox! 20181226
Dec 26, 2018 Review – CERV2 at Greenbuild 2018 Tags: CERV 20181226
Nov 26, 2018 News – CERV OEM Filter Store is OPEN!!! Tags: CERV, Indoor Air Quality 20181126
Nov 19, 2018 News – Check Out Our Social Media! 20181119
Oct 24, 2018 Events – Free CEU Webinar: Duct Design & Performance (PDF Download) Tags: Ducting, Energy Efficiency, Webinar 20181024
Oct 24, 2018 Featured Article – CERV2 is UL Approved! Tags: CERV 20181024
Oct 24, 2018 News – Stop by Our Booth at Greenbuild Chicago (Free Tickets!) Tags: CERV 20181024
Oct 24, 2018 Spotlight – University of Illinois Students Visit Build Equinox Tags: CERV 20181024
Jul 23, 2018 Featured Article – Happy 10th Birthday, CERV and Sunflower! Tags: CERV, Solar 20180723
Jul 23, 2018 Spotlight – Good News from El Salvador! Tags: CERV, Net Zero, Solar 20180723
Jun 22, 2018 Tech – Installing a Ductless Mini-split Tags: Heat Pump 20180622
Jun 22, 2018 Featured Article – Mini-split Mania! Tags: Heat Pump 20180622
Apr 30, 2018 News – Now offering on-demand webinars for CEUs! 20180430
Apr 30, 2018 Events – Free CEU Webinar! (May 2, 2018) 20180430
Apr 30, 2018 Featured Article – Ductology Part 2 Tags: Ducting, Report, Ventilation 20180430
Feb 19, 2018 Review – 2018 Better Buildings by Design Conference, Flu and Colds 20180219
Feb 19, 2018 Featured Article – Hot Water! Tags: Comfort, Water 20180219
Jan 22, 2018 Events – Visit us at BuildingEnergy Boston! (March 7-9, Boston, MA) 20180122
Jan 22, 2018 Events – Efficiency Vermont Better Buildings by Design Conference (Feb 7-8) 20180122
Jan 22, 2018 Featured Article – Ductology (Part 1) Tags: Ducting, Report, Ventilation 20180122
Nov 20, 2017 Featured Article – Heat Pump (Hybrid) Clothes Dryers are Coming! Tags: Heat Pump 20171120
Oct 31, 2017 Featured Article – CERV2 Measures IAQ at NAPHC & NAPHN 20171031
Sep 25, 2017 Featured Article – Introducing CERV2 Tags: CERV 20170925
Aug 21, 2017 Events – Free CEU Webinar! (Sep 27, 2017) 20170821
Aug 21, 2017 Featured Article – Quiz 20170821
Jul 27, 2017 Events – New IAQ Metrics Webinar (Video + PDF) Tags: Health, Indoor Air Quality, Ventilation 20170727
Jul 25, 2017 Featured Article – Endotoxins: Small But Very Significant Tags: Health, Indoor Air Quality, Report, Ventilation 20170725
May 22, 2017 Events – Economical Net Zero Design Webinar (Video+PDF) Tags: Energy Efficiency, Net Zero, Webinar, ZEROs 20170522
May 22, 2017 Featured Article – Styrax Japonicus 20170522
Apr 28, 2017 Events – 7 Steps for Designing an Economical Net Zero Home (Video + PDF) Tags: Energy Efficiency, Net Zero, Webinar, ZEROs 20170428
Apr 28, 2017 Featured Article – Engineering Net Zero Homes Tags: Net Zero, ZEROs 20170428
Mar 20, 2017 Featured Article – Build Equinox Zero Plus Facility Tags: Energy Efficiency, Net Zero, Solar 20170320
Feb 14, 2017 Featured Article – February Flu Tags: Health, Indoor Air Quality, Report, Ventilation 20170214
Jan 20, 2017 Events – HRV, ERV and Smart Vent Systems, Free CEU Webinar (Feb 15) Tags: CERV, Energy Efficiency, Ventilation, Webinar 20170120
Jan 20, 2017 Events – NESEA IAQ Metrics Presentation (Mar 9, Boston, MA) Tags: Health, Indoor Air Quality 20170120
Jan 19, 2017 Featured Article – The Perfect Dust Storm Tags: Health, Indoor Air Quality, Report, Ventilation 20170119
Jan 12, 2017 Events – Efficiency Vermont Better Buildings by Design Conference (Feb 1-2) Tags: CERV 20170112
Dec 26, 2016 Featured Article – Happy Holidays from Build Equinox! 20161226
Nov 29, 2016 Featured Article – Geo-Boost Tags: CERV, Energy Efficiency 20161129
Nov 29, 2016 Spotlight – This Old Passive House Tags: Energy Efficiency, Passive House, Ventilation 20161129
Nov 29, 2016 Review – House Music 20161129
Oct 28, 2016 Featured Article – Comparing ERV, HRV, and CERV Tags: CERV, Energy Efficiency, Heat Pump, Ventilation 20161028
Oct 28, 2016 Spotlight – Net Zero Eco-House (Monticello, IL) Tags: CERV, Energy Efficiency, Net Zero, Passive House 20161028
Oct 28, 2016 Spotlight – Forty Under 40 20161028
Sep 28, 2016 Events – Free CEU Webinar (Oct 5th): Why are new Indoor Air Quality metrics needed? Tags: Health, Indoor Air Quality, Ventilation 20160928
Sep 28, 2016 Review – 2016 North American Passive House Conference Tags: Passive House 20160928
Sep 28, 2016 Featured Article – New CERV-ICE IAQ Analytics Released! Tags: CERV, Health, Indoor Air Quality 20160928
Sep 28, 2016 Spotlight – CERVs in Passive Homes, pt. 2 Tags: CERV, Passive House 20160928
Aug 18, 2016 Featured Article – Understanding the House as a System Tags: Comfort, Energy Efficiency, Humidity, Indoor Air Quality, Net Zero, Ventilation 20160818
Aug 18, 2016 Spotlight – CERVs in Passive Homes Tags: CERV, Passive House 20160818
Aug 18, 2016 Review – “What is IAQ?”, P. Ole Fanger Tags: Indoor Air Quality 20160818
Aug 18, 2016 Tech – CERV CO2/VOC Library Tags: CERV, CO2, Health, Indoor Air Quality, Report, VOC 20160818
Jul 19, 2016 Events – September North American Passive House Conference Tags: Passive House 20160719
Jul 18, 2016 News – CERV Website Tags: CERV 20160718
Jul 18, 2016 Featured Article – VERMOD CERV Report Released Tags: CERV, Energy Efficiency, Indoor Air Quality, Report 20160718
Jul 18, 2016 Review – LBNL report: “Houses are Dumb Without Smart Ventilation” Tags: Indoor Air Quality, Report, Ventilation 20160718
Jul 18, 2016 Spotlight – Professor P. Ole Fanger (1934-2006); IAQ and Comfort Pioneer Tags: Comfort, Indoor Air Quality 20160718
Jul 18, 2016 Tech Note – Airflow Calculation for Ventilation Systems Tags: Ducting, Report, Ventilation 20160718

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