Performance of Revised Duct Design, Save Money and Cool Customers

Performance of Revised Duct Design, Save Money and Cool Customers RESNET February 24, 2010 ASU Technology Dept. and Energy Center Jeff Tiller, Sean Gray, Erica Porras, Andrew Windham, Bruce Davis

Heating and AC Systems Should Be Designed Right

Standard Approach

Is This Working?

Problems Between Floors

Chases Take up Square Footage 68 5" Ø 12" Ø T 81 7" Ø 118 7" Ø 113 7" Ø 780 14" Ø Z-2 Z-1 10" Ø 116 7" Ø 36 4" Ø 80 6" Ø 220 8" Ø

Goals Reduce some costs Save some square feet Simplify installation Maintain comfort - downstairs/upstairs - within rooms

Solution to Long, Curvy Attic Ducts Bring in air near interior wall Upgrade ceiling diffuser xx

Standard Residential Diffusers Floor diffusers Residential ceiling diffuser

Commercial Diffusers Hart and Cooley Models CHD1 831 HVD

Noise Communication Environment Typical Occupancy Below NC 25 NC 30 NC 35 NC 40 NC 45 Above NC 50 Above NC 100 Extremely quiet environment; suppressed speech is quite audible; suitable for acute pickup of all sounds Very quiet office; suitable for large conferences; telephone use satisfactory. Quiet office; satisfactory for conference at a 15 ft. table; normal voice 10-30 ft satisfactory. Satisfactory for conferences at a 6-8 ft. table; normal voice 6-12 ft. Satisfactory for conferences at a 4-5 ft. table; normal voice 3-6 ft.; raised voice 6-12 ft.; telephone use occasionally difficult. Unsatisfactory for conference of more than two or three persons, normal voice 1-2 ft.; raised voice 3-6 ft. telephone use slightly difficult. Fun places to hang out Broadcasting studios, concert halls, music rooms. Residences, theatres, libraries, executive offices, directors rooms. Private offices, schools, hotel telephone use, rooms, courtrooms, churches, hospital rooms. General office, labs, dining rooms, telephone use satisfactory. Retail stores, cafeterias, lobby areas, large drafting & engineering offices, reception areas. Computer rooms, stenographic pools, print machine rooms, process areas Bars in Austin

NC 30 NC 35 NC40 NC45 Residences, very Quiet offices General Retail quiet offices offices stores

Velocity, Throw, CFM A411 Floor Diffuser 4x10 velocity 300 400 500 600 700 800 900 cfm 50 70 85 100 120 135 155 throw (ft) 4 6 7.5 9 11 12 13.5 A501 Residential Ceiling Diffuser -- 6x6 velocity 400 500 600 700 900 1,100 1,500 cfm 55 65 75 90 120 140 195 throw (ft) 5 6 7 8 10 12 15 831 Commercial Register 10 x 4 velocity 400 500 600 700 800 900 1,000 cfm 80 100 120 140 160 180 200 throw (ft) 7 9 11 13 14 16 18

Hypothesis 1 In a two story home with an open stairwell and one dual-zoned system with a properly sized upstairs return it is unnecessary to provide a return in the downstairs space

Hypothesis 2 Changing to curved blade supply diffusers relocated to interior walls of rooms will provide comparable room air temperature distributions to traditional exterior wall locations

Issues Current code guidance? What is necessary to make code changes?

Current Code Guidance 2009 NC Mechanical Code 918.10 Return-air intake (nonengineered systems) -One intake per level -One intake per 1600 sf -Located in area served -No restrictions such as solid door

Effective January 1, 2010 NC State Board of Examiners Heating Contractors -Room by room load calculation -Max temp difference 4 degrees F -floor to floor -room to room Documents available for 6 years

What is Necessary to Make Changes? Prior to a code body changing code language it is necessary to provide field documented research that comfortably addresses the concerns in the current code This case study is contributing to that process

Initial Case Study - Townhomes Intervention #84 left nonintervention #85 right

Modifications

Confirm Air Flows

Initial Case Study - Townhomes Intervention #84 left nonintervention #85 right

Data Collection

Data Collection Sensor Locations Air Return Supply Diffuser Sensor Stand Gateway

7/13/09 2:00 PM 7/13/09 2:36 PM 7/13/09 3:12 PM 7/13/09 3:48 PM 7/13/09 4:24 PM 7/13/09 5:00 PM 7/13/09 5:36 PM 7/13/09 6:12 PM 7/13/09 6:48 PM 7/13/09 7:24 PM 7/13/09 8:00 PM 7/13/09 8:36 PM 7/13/09 9:12 PM 7/13/09 9:48 PM 7/13/09 10:24 PM 7/13/09 11:00 PM 7/13/09 11:36 PM 7/14/09 12:12 AM 7/14/09 12:48 AM 7/14/09 1:24 AM 7/14/09 2:00 AM 7/14/09 2:36 AM 7/14/09 3:12 AM 7/14/09 3:48 AM 7/14/09 4:24 AM 7/14/09 5:00 AM 7/14/09 5:36 AM 7/14/09 6:12 AM 7/14/09 6:48 AM 7/14/09 7:24 AM 7/14/09 8:00 AM 7/14/09 8:36 AM 7/14/09 9:12 AM 7/14/09 9:48 AM 7/14/09 10:24 AM 7/14/09 11:00 AM 7/14/09 11:36 AM 7/14/09 12:12 PM 7/14/09 12:48 PM 7/14/09 1:24 PM 7/14/09 2:00 PM 7/14/09 2:36 PM 7/14/09 3:12 PM 7/14/09 3:48 PM 7/14/09 4:24 PM 7/14/09 5:00 PM 7/14/09 5:36 PM 7/14/09 6:12 PM 7/14/09 6:48 PM 7/14/09 7:24 PM 7/14/09 8:00 PM 7/14/09 8:36 PM 7/14/09 9:12 PM 7/14/09 9:48 PM 7/14/09 10:24 PM 7/14/09 11:00 PM 7/14/09 11:36 PM 7/15/09 12:12 AM 7/15/09 12:48 AM 7/15/09 1:24 AM 7/15/09 2:00 AM 7/15/09 2:36 AM 7/15/09 3:12 AM 7/15/09 3:48 AM 7/15/09 4:24 AM 7/15/09 5:00 AM 7/15/09 5:36 AM 7/15/09 6:12 AM 7/15/09 6:48 AM 7/15/09 7:24 AM 7/15/09 8:00 AM 7/15/09 8:36 AM 7/15/09 9:12 AM 7/15/09 9:48 AM 7/15/09 10:24 AM 7/15/09 11:00 AM 7/15/09 11:36 AM 7/15/09 12:12 PM 7/15/09 12:48 PM 7/15/09 1:24 PM 7/15/09 2:00 PM Temperature Scale - Degrees in Fahrenheit 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 Difference in Maximum and Minimum Temperatures Upstairs Hallway vs. All Downstairs Sensors Time Scale - Eastern Daylight Saving Time Intervention Unit 84 Base Unit 85

7/13/09 2:00 PM 7/13/09 2:36 PM 7/13/09 3:12 PM 7/13/09 3:48 PM 7/13/09 4:24 PM 7/13/09 5:00 PM 7/13/09 5:36 PM 7/13/09 6:12 PM 7/13/09 6:48 PM 7/13/09 7:24 PM 7/13/09 8:00 PM 7/13/09 8:36 PM 7/13/09 9:12 PM 7/13/09 9:48 PM 7/13/09 10:24 PM 7/13/09 11:00 PM 7/13/09 11:36 PM 7/14/09 12:12 AM 7/14/09 12:48 AM 7/14/09 1:24 AM 7/14/09 2:00 AM 7/14/09 2:36 AM 7/14/09 3:12 AM 7/14/09 3:48 AM 7/14/09 4:24 AM 7/14/09 5:00 AM 7/14/09 5:36 AM 7/14/09 6:12 AM 7/14/09 6:48 AM 7/14/09 7:24 AM 7/14/09 8:00 AM 7/14/09 8:36 AM 7/14/09 9:12 AM 7/14/09 9:48 AM 7/14/09 10:24 AM 7/14/09 11:00 AM 7/14/09 11:36 AM 7/14/09 12:12 PM 7/14/09 12:48 PM 7/14/09 1:24 PM 7/14/09 2:00 PM 7/14/09 2:36 PM 7/14/09 3:12 PM 7/14/09 3:48 PM 7/14/09 4:24 PM 7/14/09 5:00 PM 7/14/09 5:36 PM 7/14/09 6:12 PM 7/14/09 6:48 PM 7/14/09 7:24 PM 7/14/09 8:00 PM 7/14/09 8:36 PM 7/14/09 9:12 PM 7/14/09 9:48 PM 7/14/09 10:24 PM 7/14/09 11:00 PM 7/14/09 11:36 PM 7/15/09 12:12 AM 7/15/09 12:48 AM 7/15/09 1:24 AM 7/15/09 2:00 AM 7/15/09 2:36 AM 7/15/09 3:12 AM 7/15/09 3:48 AM 7/15/09 4:24 AM 7/15/09 5:00 AM 7/15/09 5:36 AM 7/15/09 6:12 AM 7/15/09 6:48 AM 7/15/09 7:24 AM 7/15/09 8:00 AM 7/15/09 8:36 AM 7/15/09 9:12 AM 7/15/09 9:48 AM 7/15/09 10:24 AM 7/15/09 11:00 AM 7/15/09 11:36 AM 7/15/09 12:12 PM 7/15/09 12:48 PM 7/15/09 1:24 PM 7/15/09 2:00 PM Temperature Scale Degree in Fahrenheit 76.0 75.5 75.0 74.5 74.0 73.5 73.0 72.5 72.0 71.5 71.0 Master Bedroom Stand 4 at 6ft Intervention Unit 84 Base Unit 85 Time Scale - Eastern Daylight Saving Time

7/13/09 2:00 PM 7/13/09 2:36 PM 7/13/09 3:12 PM 7/13/09 3:48 PM 7/13/09 4:24 PM 7/13/09 5:00 PM 7/13/09 5:36 PM 7/13/09 6:12 PM 7/13/09 6:48 PM 7/13/09 7:24 PM 7/13/09 8:00 PM 7/13/09 8:36 PM 7/13/09 9:12 PM 7/13/09 9:48 PM 7/13/09 10:24 PM 7/13/09 11:00 PM 7/13/09 11:36 PM 7/14/09 12:12 AM 7/14/09 12:48 AM 7/14/09 1:24 AM 7/14/09 2:00 AM 7/14/09 2:36 AM 7/14/09 3:12 AM 7/14/09 3:48 AM 7/14/09 4:24 AM 7/14/09 5:00 AM 7/14/09 5:36 AM 7/14/09 6:12 AM 7/14/09 6:48 AM 7/14/09 7:24 AM 7/14/09 8:00 AM 7/14/09 8:36 AM 7/14/09 9:12 AM 7/14/09 9:48 AM 7/14/09 10:24 AM 7/14/09 11:00 AM 7/14/09 11:36 AM 7/14/09 12:12 PM 7/14/09 12:48 PM 7/14/09 1:24 PM 7/14/09 2:00 PM 7/14/09 2:36 PM 7/14/09 3:12 PM 7/14/09 3:48 PM 7/14/09 4:24 PM 7/14/09 5:00 PM 7/14/09 5:36 PM 7/14/09 6:12 PM 7/14/09 6:48 PM 7/14/09 7:24 PM 7/14/09 8:00 PM 7/14/09 8:36 PM 7/14/09 9:12 PM 7/14/09 9:48 PM 7/14/09 10:24 PM 7/14/09 11:00 PM 7/14/09 11:36 PM 7/15/09 12:12 AM 7/15/09 12:48 AM 7/15/09 1:24 AM 7/15/09 2:00 AM 7/15/09 2:36 AM 7/15/09 3:12 AM 7/15/09 3:48 AM 7/15/09 4:24 AM 7/15/09 5:00 AM 7/15/09 5:36 AM 7/15/09 6:12 AM 7/15/09 6:48 AM 7/15/09 7:24 AM 7/15/09 8:00 AM 7/15/09 8:36 AM 7/15/09 9:12 AM 7/15/09 9:48 AM 7/15/09 10:24 AM 7/15/09 11:00 AM 7/15/09 11:36 AM 7/15/09 12:12 PM 7/15/09 12:48 PM 7/15/09 1:24 PM 7/15/09 2:00 PM Temperature Scale Degrees in Fahrenheit 78.0 77.5 77.0 76.5 76.0 75.5 75.0 74.5 74.0 73.5 73.0 72.5 72.0 71.5 71.0 Dining Room at 6ft Time Scale Eastern Daylight Saving Time Intervention Unit 84 Base Unit 85

7/13/09 2:00 PM 7/13/09 2:36 PM 7/13/09 3:12 PM 7/13/09 3:48 PM 7/13/09 4:24 PM 7/13/09 5:00 PM 7/13/09 5:36 PM 7/13/09 6:12 PM 7/13/09 6:48 PM 7/13/09 7:24 PM 7/13/09 8:00 PM 7/13/09 8:36 PM 7/13/09 9:12 PM 7/13/09 9:48 PM 7/13/09 10:24 PM 7/13/09 11:00 PM 7/13/09 11:36 PM 7/14/09 12:12 AM 7/14/09 12:48 AM 7/14/09 1:24 AM 7/14/09 2:00 AM 7/14/09 2:36 AM 7/14/09 3:12 AM 7/14/09 3:48 AM 7/14/09 4:24 AM 7/14/09 5:00 AM 7/14/09 5:36 AM 7/14/09 6:12 AM 7/14/09 6:48 AM 7/14/09 7:24 AM 7/14/09 8:00 AM 7/14/09 8:36 AM 7/14/09 9:12 AM 7/14/09 9:48 AM 7/14/09 10:24 AM 7/14/09 11:00 AM 7/14/09 11:36 AM 7/14/09 12:12 PM 7/14/09 12:48 PM 7/14/09 1:24 PM 7/14/09 2:00 PM 7/14/09 2:36 PM 7/14/09 3:12 PM 7/14/09 3:48 PM 7/14/09 4:24 PM 7/14/09 5:00 PM 7/14/09 5:36 PM 7/14/09 6:12 PM 7/14/09 6:48 PM 7/14/09 7:24 PM 7/14/09 8:00 PM 7/14/09 8:36 PM 7/14/09 9:12 PM 7/14/09 9:48 PM 7/14/09 10:24 PM 7/14/09 11:00 PM 7/14/09 11:36 PM 7/15/09 12:12 AM 7/15/09 12:48 AM 7/15/09 1:24 AM 7/15/09 2:00 AM 7/15/09 2:36 AM 7/15/09 3:12 AM 7/15/09 3:48 AM 7/15/09 4:24 AM 7/15/09 5:00 AM 7/15/09 5:36 AM 7/15/09 6:12 AM 7/15/09 6:48 AM 7/15/09 7:24 AM 7/15/09 8:00 AM 7/15/09 8:36 AM 7/15/09 9:12 AM 7/15/09 9:48 AM 7/15/09 10:24 AM 7/15/09 11:00 AM 7/15/09 11:36 AM 7/15/09 12:12 PM 7/15/09 12:48 PM 7/15/09 1:24 PM 7/15/09 2:00 PM Temperature Scale Degrees in Fahrenheit 78.0 77.5 77.0 76.5 76.0 75.5 75.0 74.5 74.0 73.5 73.0 72.5 72.0 71.5 71.0 Downstairs Thermostat at 6ft Intervention Unit 84 Base Unit 85 Time Scale - Eastern Daylight Saving Time

7/13/09 2:00 PM 7/13/09 2:36 PM 7/13/09 3:12 PM 7/13/09 3:48 PM 7/13/09 4:24 PM 7/13/09 5:00 PM 7/13/09 5:36 PM 7/13/09 6:12 PM 7/13/09 6:48 PM 7/13/09 7:24 PM 7/13/09 8:00 PM 7/13/09 8:36 PM 7/13/09 9:12 PM 7/13/09 9:48 PM 7/13/09 10:24 PM 7/13/09 11:00 PM 7/13/09 11:36 PM 7/14/09 12:12 AM 7/14/09 12:48 AM 7/14/09 1:24 AM 7/14/09 2:00 AM 7/14/09 2:36 AM 7/14/09 3:12 AM 7/14/09 3:48 AM 7/14/09 4:24 AM 7/14/09 5:00 AM 7/14/09 5:36 AM 7/14/09 6:12 AM 7/14/09 6:48 AM 7/14/09 7:24 AM 7/14/09 8:00 AM 7/14/09 8:36 AM 7/14/09 9:12 AM 7/14/09 9:48 AM 7/14/09 10:24 AM 7/14/09 11:00 AM 7/14/09 11:36 AM 7/14/09 12:12 PM 7/14/09 12:48 PM 7/14/09 1:24 PM 7/14/09 2:00 PM 7/14/09 2:36 PM 7/14/09 3:12 PM 7/14/09 3:48 PM 7/14/09 4:24 PM 7/14/09 5:00 PM 7/14/09 5:36 PM 7/14/09 6:12 PM 7/14/09 6:48 PM 7/14/09 7:24 PM 7/14/09 8:00 PM 7/14/09 8:36 PM 7/14/09 9:12 PM 7/14/09 9:48 PM 7/14/09 10:24 PM 7/14/09 11:00 PM 7/14/09 11:36 PM 7/15/09 12:12 AM 7/15/09 12:48 AM 7/15/09 1:24 AM 7/15/09 2:00 AM 7/15/09 2:36 AM 7/15/09 3:12 AM 7/15/09 3:48 AM 7/15/09 4:24 AM 7/15/09 5:00 AM 7/15/09 5:36 AM 7/15/09 6:12 AM 7/15/09 6:48 AM 7/15/09 7:24 AM 7/15/09 8:00 AM 7/15/09 8:36 AM 7/15/09 9:12 AM 7/15/09 9:48 AM 7/15/09 10:24 AM 7/15/09 11:00 AM 7/15/09 11:36 AM 7/15/09 12:12 PM 7/15/09 12:48 PM 7/15/09 1:24 PM 7/15/09 2:00 PM Temperature Scale Degrees in Fahrenheit 78.0 77.5 77.0 76.5 76.0 75.5 75.0 74.5 74.0 73.5 73.0 72.5 72.0 71.5 71.0 Time Scale - Eastern Daylight Saving Time Intervention Unit 84 Base Unit 85

7/13/09 2:00 PM 7/13/09 2:36 PM 7/13/09 3:12 PM 7/13/09 3:48 PM 7/13/09 4:24 PM 7/13/09 5:00 PM 7/13/09 5:36 PM 7/13/09 6:12 PM 7/13/09 6:48 PM 7/13/09 7:24 PM 7/13/09 8:00 PM 7/13/09 8:36 PM 7/13/09 9:12 PM 7/13/09 9:48 PM 7/13/09 10:24 PM 7/13/09 11:00 PM 7/13/09 11:36 PM 7/14/09 12:12 AM 7/14/09 12:48 AM 7/14/09 1:24 AM 7/14/09 2:00 AM 7/14/09 2:36 AM 7/14/09 3:12 AM 7/14/09 3:48 AM 7/14/09 4:24 AM 7/14/09 5:00 AM 7/14/09 5:36 AM 7/14/09 6:12 AM 7/14/09 6:48 AM 7/14/09 7:24 AM 7/14/09 8:00 AM 7/14/09 8:36 AM 7/14/09 9:12 AM 7/14/09 9:48 AM 7/14/09 10:24 AM 7/14/09 11:00 AM 7/14/09 11:36 AM 7/14/09 12:12 PM 7/14/09 12:48 PM 7/14/09 1:24 PM 7/14/09 2:00 PM 7/14/09 2:36 PM 7/14/09 3:12 PM 7/14/09 3:48 PM 7/14/09 4:24 PM 7/14/09 5:00 PM 7/14/09 5:36 PM 7/14/09 6:12 PM 7/14/09 6:48 PM 7/14/09 7:24 PM 7/14/09 8:00 PM 7/14/09 8:36 PM 7/14/09 9:12 PM 7/14/09 9:48 PM 7/14/09 10:24 PM 7/14/09 11:00 PM 7/14/09 11:36 PM 7/15/09 12:12 AM 7/15/09 12:48 AM 7/15/09 1:24 AM 7/15/09 2:00 AM 7/15/09 2:36 AM 7/15/09 3:12 AM 7/15/09 3:48 AM 7/15/09 4:24 AM 7/15/09 5:00 AM 7/15/09 5:36 AM 7/15/09 6:12 AM 7/15/09 6:48 AM 7/15/09 7:24 AM 7/15/09 8:00 AM 7/15/09 8:36 AM 7/15/09 9:12 AM 7/15/09 9:48 AM 7/15/09 10:24 AM 7/15/09 11:00 AM 7/15/09 11:36 AM 7/15/09 12:12 PM 7/15/09 12:48 PM 7/15/09 1:24 PM 7/15/09 2:00 PM Temperature Scale - Fahrenheit 78.0 77.5 77.0 76.5 76.0 75.5 75.0 74.5 74.0 73.5 73.0 72.5 72.0 71.5 71.0 Temperature Spread in Downstairs of Intervention Unit 84 Time Scale - Eastern Daylight Saving Time 84-down.tstat-2ft 84-down.tstat-6ft 84-up.stairs-2ft 84-up.stairs-6ft 84-down.stairs-2ft 84-down.stairs-6ft 84-fireplace-2ft 84-fireplace-6ft 84-dine-2ft 84-dine-6ft 84-kitchen-2ft

7/13/09 2:00 PM 7/13/09 2:36 PM 7/13/09 3:12 PM 7/13/09 3:48 PM 7/13/09 4:24 PM 7/13/09 5:00 PM 7/13/09 5:36 PM 7/13/09 6:12 PM 7/13/09 6:48 PM 7/13/09 7:24 PM 7/13/09 8:00 PM 7/13/09 8:36 PM 7/13/09 9:12 PM 7/13/09 9:48 PM 7/13/09 10:24 PM 7/13/09 11:00 PM 7/13/09 11:36 PM 7/14/09 12:12 AM 7/14/09 12:48 AM 7/14/09 1:24 AM 7/14/09 2:00 AM 7/14/09 2:36 AM 7/14/09 3:12 AM 7/14/09 3:48 AM 7/14/09 4:24 AM 7/14/09 5:00 AM 7/14/09 5:36 AM 7/14/09 6:12 AM 7/14/09 6:48 AM 7/14/09 7:24 AM 7/14/09 8:00 AM 7/14/09 8:36 AM 7/14/09 9:12 AM 7/14/09 9:48 AM 7/14/09 10:24 AM 7/14/09 11:00 AM 7/14/09 11:36 AM 7/14/09 12:12 PM 7/14/09 12:48 PM 7/14/09 1:24 PM 7/14/09 2:00 PM 7/14/09 2:36 PM 7/14/09 3:12 PM 7/14/09 3:48 PM 7/14/09 4:24 PM 7/14/09 5:00 PM 7/14/09 5:36 PM 7/14/09 6:12 PM 7/14/09 6:48 PM 7/14/09 7:24 PM 7/14/09 8:00 PM 7/14/09 8:36 PM 7/14/09 9:12 PM 7/14/09 9:48 PM 7/14/09 10:24 PM 7/14/09 11:00 PM 7/14/09 11:36 PM 7/15/09 12:12 AM 7/15/09 12:48 AM 7/15/09 1:24 AM 7/15/09 2:00 AM 7/15/09 2:36 AM 7/15/09 3:12 AM 7/15/09 3:48 AM 7/15/09 4:24 AM 7/15/09 5:00 AM 7/15/09 5:36 AM 7/15/09 6:12 AM 7/15/09 6:48 AM 7/15/09 7:24 AM 7/15/09 8:00 AM 7/15/09 8:36 AM 7/15/09 9:12 AM 7/15/09 9:48 AM 7/15/09 10:24 AM 7/15/09 11:00 AM 7/15/09 11:36 AM 7/15/09 12:12 PM 7/15/09 12:48 PM 7/15/09 1:24 PM 7/15/09 2:00 PM Temperature Scale - Fahrenheit 78.0 77.5 77.0 76.5 76.0 75.5 75.0 74.5 74.0 73.5 73.0 72.5 72.0 71.5 71.0 Temperature Spread in Downstairs of Base Unit 85 Time Scale - Eastern Daylight Saving Time 85-down.tstat-2ft 85-down.tstat-2ft 85-up.stairs-2ft 85-up.stairs-6ft 85-down.stairs- 2ft 85-down.stairs- 6ft 85-up.stairs-2ft 85-fire.place-6ft 85-dine-2ft 85-dine-6ft 85-kitchen-2ft 85-kitchen-6ft 85-down.return- 2ft

Open Stairwell Air Current Result - 84

Open Stairwell Air Current Result - 84 Air handler - off

Open Stairwell Air Current Result - 85

Discussion What about larger homes? What about air velocity at stairs in larger homes? What about larger rooms? What about heating season?

Discussion Can revised duct design [chase space available] add to the potential of moving the Air Handler out of the attic? Will 30% more efficient homes allow for reducing duct diameter and thus make placing ducts in floor truss locations easier?

Discussion Will curved blade supply diffusers with shorter duct lengths be seen as positive by adding flexibility to boot placement

Things you find out later I don t see how this can work

Conclusions Positive outcomes from this case study - review More examples necessary to work out the details for - non-engineered systems Mobile data collection protocol established (remember the Jan 1 changes)