Adventures In Building Science...ASHRAE Standard 62.2 calls for 7.5 cfm per person plus 0.03 cfm per square foot of conditioned area Occupancy is deemed to be the number of bedrooms

Building Science

Adventures In Building Science

Joseph Lstiburek, Ph.D, P.Eng, ASHRAE Fellow

www.buildingscience.com

Building Science CorporationJoseph Lstiburek 2

Mechanical Systems


Mechanical SystemsCooling System To Make It Cold


Mechanical SystemsCooling System To Make It ColdDehumidification System To Make It Dry


Mechanical SystemsCooling System To Make It ColdDehumidification System To Make It DryHeating System To Make It Warm


Mechanical SystemsCooling System To Make It ColdDehumidification System To Make It DryHeating System To Make It WarmEnergy Recovery System To Keep It Cold

and Dry and Warm and Comfortable



and Dry and Warm and ComfortableDistribution System To Make It Uniform



and Dry and Warm and ComfortableDistribution System To Make It UniformRange Hoods Are A Special Kind of Hell


Don’t Try to Combine Them…...



Build Tight - Ventilate Right


Build Tight - Ventilate RightHow Tight?What’s Right?


Air Barrier Metrics

Material 0.02 l/(s-m2) @ 75 PaAssembly 0.20 l/(s-m2) @ 75 PaEnclosure 2.00 l/(s-m2) @ 75 Pa

0.25 cfm/ft2 @ 50 Pa


Getting rid of big holes 3 ach@50Getting rid of smaller holes 1.5 ach@50Getting German 0.6 ach@50


Best

As Tight as Possible - with -Balanced VentilationEnergy RecoveryDistribution and MixingSource Control - Spot exhaust ventilation

FiltrationMaterial selection


Worst

Leaky - with – NothingSpot Ventilation in Bathroom/KitchenExhaust Ventilation – with – No Distribution

and No Mixing


Three Types of Controlled Ventilation Systems

Exhaust VentilationSupply VentilationBalanced Ventilation











Ventilation Rates Are Based on Odor Control


Ventilation Rates Are Based on Odor ControlHealth Science Basis for Ventilation Rates is

Extremely Limited



Extremely LimitedAlmost Nothing Cited Applies to Housing



Extremely LimitedAlmost Nothing Cited Applies to HousingThe Applicable Studies Focus on Dampness

Building Science Corporation23)$45*6)&-7'($8**>R

Building Science Corporation23)$45*6)&-7'($8**>9

House2,000 ft2

3 bedrooms8 ft. ceilingVolume: 16,000 ft3

.35 ach 93 cfm

.30 ach 80 cfm

.25 ach 67 cfm

.20 ach 53 cfm

.15 ach 40 cfm


!"#$%&'((()*+&

,)-%./""0$1)*+2)3%454678"5#0%9):;'((()*+,

Q>D*;15*****N>*1C=Q>S*;15*****MS*1C=Q9D*;15*****GK*1C=Q9S*;15*****D>*1C=QRD*;15*****AS*1C=

8%6+45<+4"6)=<+%$G9*T K> D*1C=X4$()3% 9S*1C=

RS*1C=X4$()3% AS*1C=G9*T MN RD*1C=X4$()3% GS*1C=

Q>D*;15 NS*1C=G9Q9*T 9SRS KQD*1C=X4$()3%********DS*1C=

c*SQSRG9Q9*T 9SR> KQD*1C=X4$()3%********NS*1C=

c*SQS>

G9* MN RD*1C=X4$()3% GS*1C=

Building Science Corporation23)$45*6)&-7'($8**>A

OfficeOccupant Density

15/1000 ft2 (67 ft2/person) 62 - 8915 cfm/person

5/1000 ft2 (200 ft2/person) 62.1 - 200717 cfm/person

Correctional Facility CellOccupant Density

20/1000 ft2 (48 ft2/person) 62.1 – 200710 cfm/person

B2D2)E<75"#!</F</.)G3H""5)"*)D#-543)!%<5+H:I,;:IJJ

RDS*C&> 9S*1C=X4$()3%

>SS*C&> R9*1C=X4$()3%

B2D2)E<75"#!</F</.)G3H""5)"*)D#-543)!%<5+H:I,;:IJJ

RDS*C&> 9S*1C=X4$()3%*RMQKD*C&9 RSG*311'4;%&)

>SS*C&> R9*1C=X4$()3%*>KQD*C&9 D>*311'4;%&)

KL?%/40%6+

AKS*C&> DN*C&9

9SS*C&> 9D*C&9

RSS*C&> R9*C&9


,'-."-%/*01-$%1$*?3(43(;&-3%23)$45*6)&-7'($8***>N

!'7-%d*BQd*F3%d*BQeQd*015.$-7-%/$(d*EQd*9SRS

,'-."-%/*01-$%1$*?3(43(;&-3%23)$45*6)&-7'($8***AS


ASHRAE Standard 62.2 calls for 7.5 cfm per person plus 0.03 cfm per square foot of conditioned area

Occupancy is deemed to be the number of bedrooms plus one


ASHRAE Standard 62.2 calls for 7.5 cfm per person plus 0.03 cfm per square foot of conditioned area


Outcome is often bad – part load humidity problems, dryness problems, energy problems


IRC 2015 and 2018 calls for 7.5 cfm per person plus 0.01 cfm per square foot of conditioned area



IRC 2021 and IMC 2021 calls for 7.5 cfm per person plus 0.01 cfm per square foot of conditioned area


Plus a 30 percent credit for balanced ventilation and distribution


3 Bedroom House – 2,500 ft230 cfm plus 75 cfm 105 cfm


3 Bedroom House – 2,500 ft230 cfm plus 25 cfm 55 cfm


3 Bedroom House – 2,500 ft230 cfm plus 25 cfm 55 cfm55 cfm x 0.7 = 38.5 cfm


The Cult of The Blower Door



Blower Door Can’t Get You The True ACHOn A Short Term Basis – Hour, Day, Week


Don’t Know Where The Holes AreDon’t Know The Type of HolesDon’t Know The Pressure Across The Holes




Dilution Is Not The Solution To Indoor Pollution

Source Control


Dilution For PeopleSource Control For The Building


Recommended Range of Relative HumidityAbove 25 percent during winterBelow 70 percent during summer

Building Science CorporationJoseph Lstiburek – HVAC 58



Kitchen Exhaust Hoods














Clothes Dryers




Fireplaces






Approaches













Building Science Corporation Joseph Lstiburek 94


















Building Science Corporation Joseph Lstiburek – HVAC 112




















Building Science CorporatonJoseph Lstiburek – HVAC 132

















Building Science Corporation2010 Joseph Lstiburek 149

Building Science Corporation2010 Joseph Lstiburek 150


Building Science CorporationJoseph Lstiburek – Airflow 152










Duct Leakage Should Be Less Than 5% of Rated Flow As Tested By Pressurization To 25 Pascals




































Documents

Adventures In Building Science...ASHRAE Standard 62.2 calls for 7.5 cfm per person plus 0.03 cfm per square foot of conditioned area Occupancy is deemed to be the number of bedrooms