Centigrade s Testing & Training Facility Sponsored by:

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1 Welcome to AIRAH WA s Site Visit Centigrade s Testing & Training Facility Sponsored by:

2 Upcoming AIRAH WA Events AIRAH WA Members Annual Lunch Tuesday, October 16 Aloft Hotel, Rivervale Limited places remain AIRAH WA Site Visit Tuesday, November 13 ifly TBC AIRAH WA President Shout Northbridge Brewing Co Tuesday, November 27 AIRAH WA Members Golf Day Thursday, March 21, 2019 Maylands Peninsula Golf Course

3 Presenting: Michael Anthony, M. AIRAH; Tony Anderson, M.AIRAH; David Lee, M. AIRAH; Michael Snook, Affil.AIRAH; David Hammond, Stud.AIRAH; Nathan Johnsen, Affil.AIRAH; Thomas Fellows, Stud.AIRAH and Scott Hobbs

4 Effective Airside Commissioning Michael Snook Affil. AIRAH David Hammond Stud. AIRAH

5 What is Commissioning? The advancement of an installation from the state of static completion to full working order to specified requirements. It includes setting to work of an installation, and regulation of all the system flowrates. CIBSE Commissioning Code A:1996 (2006)

6 Why is Effective HVAC Commissioning Important? Courtesy HVAC HESS, 2013

7 Key Considerations Prior to Commissioning Air Systems Type of facility HVAC system is serving Allowable tolerances / permissible deviations from design requirements Access to equipment Site cleanliness Commissioning timeframe Schedule clashes

8 Common Issues Faced at Precommissioning Site not ready (Builder, Installation, No power) Volume control dampers not open Fans not bump tested / fan rotation backwards Implementation of a commissioning management plan allows the roles and responsibilities of each stakeholder to be clearly defined.

9 Hierarchy of Airside Commissioning

10 Primary Data A full system pitot traverse gives the most accurate representation of system performance Pitot traverse relies on an average measurement of velocity pressure at a section of duct with a laminar flow characteristic Where duct velocities are below 3.5m/s, a hotwire anemometer is the preferable choice₁

11 Pitot Tube Operating Principle

12 Pitot Tube Operating Principle Courtesy BSRIA BG 49/2015

13 Courtesy BSRIA BG 49/2015 Test Point Locations

14 Courtesy BSRIA BG 49/2015

15 Courtesy BSRIA BG 49/2015

16 Methods to Ensure Accurate Traverse Measurements Favour pitot tube over hotwire anemometer where there is a risk of air swirl Correctly measure internal duct dimensions Space test points methodically Log-Tchebycheff Method of Traverse vs Equal Duct Method

17 Secondary / Tertiary Data Supports primary data (Traverse) External static pressure (Fan Curve) Static profile of air system (E.G Coil PP) Fan running current Air Balance Tying several data types together ensures a true representation of system performance has been shown.

18 Fan Curves

19 Proportional Air Balancing The process of bringing the fluid flow rates throughout a distribution system into balance with one another, in their correct proportions and within tolerances specified by the designer BSRIA BG

20 Setting Fan Volume Following pre commissioning, fan is set to 110% of design for proportional balancing as a rule of thumb Use of affinity laws / static pressures handy in setting flowrate at this stage

21 Initial Scan Knowing air volume from main traverse, each terminal is measured The difference between traverse reading and sum of outlet readings is recorded. An index is identified, and a proportional balance is undertaken to bring all outlets to within a specified tolerance of design.

22 System Index The air outlet with the highest pressure loss at the design air volume. Important to consider whether the index makes sense in relation to the rest of the system. Important to physically check the duct and cushion head interface before proceeding with air balance

23 Is this an index?

24 Correction Factors A correction factor adjusts the measured readings at the terminals to reflect the true system volume. Correction factors account for: Air leakage rate Back pressure Induction within Balometer Takes into account free area of register when using vane or deflection anemometers Correction factors between 0.8 and 1.2 are generally considered acceptable (BSRIA BG )

25 Factor Caused By Hood Backpressure Courtesy Shaun Matthews Use of Correction Factors When Commissioning Air Systems, 2016

26 Factor Caused By Hood Backpressure and Cushion Head Leakage Courtesy Shaun Matthews Use of Correction Factors When Commissioning Air Systems, 2016

27 Correction Factors Not an arbitrary figure to cover up lack of volume or poor air balance Technicians need to understand why there is a deviation between measured volume at diffusion and at duct traverse. Common cause of falsified commissioning data and substandard airside commissioning. Must be verified when finalising system.

28 Case 1: Typical Cleanroom AHU Supply Air

29 Case 1: Typical Cleanroom AHU Supply Air True volume measured at laminar traverse point

30 Case 1: Typical Cleanroom AHU Supply Air Factor Ties ATBS to DTS Corrected balometer volume equals duct traverse volume

31 Likely causes of factor Factor is typical for a HEPA terminal outlet, generally caused by instrument (+ / - 3%) User factor Minimal leakage on ductwork upstream of HEPA terminals due to high static pressure on supply air ductwork

32 Case 2: Typical AHU with Swirl Diffusion

33 True supply air volume measured at laminar traverse point Case 2: Typical AHU with Swirl Diffusion

34 Case 2: Typical AHU with Swirl Diffusion Volume corrected to traverse

35 Likely Causes of Factor Swirl diffusion pattern inducting air within balometer Backpressure exerted by balometer causing restriction High backpressure of swirl diffuser causing minor leakage within cushion head- diffuser interface Instrument factor (+ / - 2%) User factor

36 Case 3: Hood Factor Used (No Traverse)

37 What if a hood factor of 1.0 was used Volume read on balometer not corrected to a traverse

38 What if a factor of 1.0 was used Established 1879L/s on balometer AHU would have to be sped up 8% to achieve this. If a traverse was taken, AHU would likely be supplying 8% more air than what was measured.

39 What does this mean? Swirl diffusion induction and back pressure within balometer causing 8% differentiation between true traverse volume and volume read on balometer. By compensating for a false reading, a power increase of 25% will be experienced as fan motor speed is increased 8%.

40 Why is this important? Key aim for any building design is to minimise energy consumption over an asset s lifecycle In facilities where maintaining specific pressure gradients is important, major issues can arise where true air volumes have not been established via a pitot traverse Control oscillation can occur as system is incorrectly commissioned Higher maintenance costs Cost of retrocommissioning vs energy savings

41 References -Alnor HVAC Assessment Handbook, 2007, USA -BSRIA BG , 2015, UK -CIBSE Commissioning Code A:1996. Chartered Institute of Building Services Engineers, (2006), UK -CIBSE Commissioning Code M. Chartered Institute of Building Services Engineers, (2003), UK -AIRAH Technical Handbook. Australian Institute of Refrigeration, Air Conditioning and Heating, 2013, Australia -Matthews. S (2016) The Use of Correction Factors When Commissioning Air Systems. Commissioning Specialists Association, West Sussex, UK -Heating, Ventilation and Air Conditioning High Efficiency Systems Strategy, P.L Lagus, P.W Butler, K.M Fleming (2006) A Comparison of Tchebycheff, Equal Area and Tracer Gas Air Flow Rate Measurements -NSW Office of Environment and Heritage (2015) HVAC Optimisation Guide, Sydney, Australia

42 Thank you for attending, please stay for refreshments. Thanks to our sponsor