2008 title 24 nonresidential hvac acceptance testing for...

2008 Title 24 Nonresidential HVAC Acceptance Testing

for Building Officials & Contractors

Presented by: name title

date

California Commissioning Collaborative

Title 24 2008 Acceptance Testing 2

What this talk will cover

•  Description of acceptance testing requirements in 2008 Title 24

•  The motivation behind the requirements

•  How acceptance testing affects design and specification practices

•  How it impacts compliance documentation

•  New responsibilities of the designer and the contractor

•  Impacts on plan review and inspection


Overview

•  Building Efficiency a product of: –  Materials and equipment

–  Installation and set-up

–  Occupant patterns and control

•  Traditional standards –  Specify materials, equipment, controls

–  Law of diminishing returns for more efficient equipment

•  2008 Title 24 standards – Acceptance Tests –  Ensure equipment works as intended


What is acceptance testing?

•  Two components of acceptance testing – Construction inspection

•  Is the specified equipment installed and calibrated?

– Functional performance testing •  Does the equipment work as intended?

•  Tests designed to uncover specification, installation or set-up problems

•  Not replacing commissioning – Commissioning = broader scope


Is acceptance testing needed?

•  PIER Small Commercial HVAC survey* •  Small commercial buildings < 4 yrs old

– 64% of economizers failed •  Cooling energy increased by 37%

– 38% of supply fans cycling during occupancy •  Violation of Title 24

– 30% unoccupied fan operation •  Increase of fan and heating energy

– 8% no outside air – 8% simultaneous heating and cooling

* http://www.energy.ca.gov/reports/2003-11-17_500-03-082.PDF


Who benefits from acceptance tests?

•  The designer –  System installed and controlled according to code design intent –  Reputation based on correct equipment operation

•  The contractor –  Technician’s work is reviewed –  Fewer call-backs

•  The owner –  Equipment works right the first time –  Energy cost savings

•  Society –  Less pollution associated with reduced energy consumption


Acceptance Tests

•  Required self-certification that equipment and systems were tested and work as intended

•  Requires someone with a license to sign off on the testing (architect, engineer or contractor)

•  Only one test (air distribution efficiency) requires 3d party verification – Home Energy Rating Service (HERS)


Resources

•  2008 Standards (Title 24) •  2008 Standards Nonresidential Appendices NA 7

–  Reference – not needed for design or testing

•  2008 Nonresidential Energy Standards Compliance Manual –  Chapter 4 – Mechanical Systems –  Chapter 10 – Acceptance Requirements –  End of Manual – Compliance and Acceptance Forms

•  CEC Resources –  http://www.energy.ca.gov/title24/2008standards/ –  CEC Bldg Standards Hotline 1-800-772-3300


Acceptance Chapter in Nonresidential Manual

•  Overview of compliance process

•  At-A-Glance – 2 page overview of test – Purpose Ø Estimated Time

– Benefits Ø Warnings or Cautions

–  Instrumentation Ø Test conditions

– Acceptance Criteria

•  Detailed test description


Acceptance and Compliance Forms

•  Compliance forms –  Filled out by designer –  MECH-1-C (C for compliance) –  Reviewed by plans checker

•  Acceptance Forms –  Filled out by person conducting test –  Reviewed by person with a license –  Usually contractor, TAB or commissioning agent –  MECH-1-A to MECH (A for acceptance) –  Collected by Inspector prior to CO (Certificate of Occupancy)

•  Forms in Appendix A of the Nonresidential Compliance Manual


Code Enforcement Process: Plans and Specifications

•  Compliance documentation with equipment specification and forms – MECH-1C lists all tests and which

equipment must be tested

– MECH-3C lists design minimum outside air •  Criteria for outside air tests (NJ.3.1 & 3.2)

•  Plan checker reviews and approves or asks for modifications – All AC systems should be listed with

appropraite tests


Code Enforcement Process: Testing and Inspection

•  Installing contractor or other “eligible professional” conducts tests and fills out MECH-#A acceptance forms –  Equipment fixed until it passes all tests

•  Completed forms handed to inspector along with other documentation –  Inspector makes sure documentation is filled out

correctly –  Incomplete documentation is returned to contractor

•  Certificate of Occupancy granted when building is in full compliance


Designer has a big impact on ease and cost of acceptance tests

•  Designer clearly identifies tests – Problem if covered equipment not specified

on MECH-1C form and later needs testing

•  Designer specifies equipment – Pre-calibrated equipment is cheaper

•  Designer builds in test capabilities – Test ports and pre-installed gauges

– Valves for isolating equipment


Key Statements in MECH-1C

•  The plans meet code

•  I am qualified to sign these forms

•  List of all mechanical acceptance tests with blanks for: – Equipment to be tested

– Checkboxes to indicate which tests apply to the equipment listed


HVAC Acceptance Tests

•  Defined in Standards’ Mandatory Section 125

•  Detailed in the Appendix NA7

•  Nonresidential Compliance Manual – Test Descriptions in Chapter 10

– Forms in Appendix A


Acceptance Requirements (1 of 2)

ACM Section and Test Standard Section

Additional Standard Section

Certificate of Acceptance

NA 7.5.1.1 Variable Air Volume Systems Outdoor Air 125(a)1 121 MECH-2A

NA 7.5.1.2 Constant Volume Systems Outdoor Air NA 7.5.2 Constant Volume Packaged HVAC Systems 125(a)2 122 MECH-3A

NA 7.5.3 Air Distribution 125(a)3 124, 144(k) or 149(b)1D MECH-4A

NA 7.5.4 (Air-Side) Economizer 125(a)4 144(e) MECH-5A

NA 7.5.5 Demand Control Ventilation 125(a)5 121(c)3&4 MECH-6A

NA 7.5.6 Supply Fan Variable Flow Controls 125(a)6 144(c)2 MECH-7A

NA 7.5.7 Valve Leakage Test 125(a)7 & 8 144(j)2 or 3 MECH-8A

NA 7.5.8 Supply Water Temperature Reset Controls 125(a)9 144(j)4 MECH-9A

NA 7.5.9 Hydronic System Variable Flow Controls 125(a)7 144(j)6 MECH-10A

NA 7.5.10 Automatic Demand Shed Controls 125(a)10 122(h) MECH-11A

Updated for 2008


New Acceptance Requirements (2 of 2) for Compliance Credit Measures

ACM Section and Test Standard Section

Additional Standard Section

Certificate of Acceptance

NA 7.5.1.11 FDD for Packaged DX Systems 125(a)11 MECH-12A

NA 7.5.1.12 FDD for AHUS and Zone Terminal Units 125(a)12 MECH-13A

NA 7.5.1.13 Distributed Energy Storage DX AC Systems 125(a)13 MECH-14A

NA 7.5.1.14 Thermal Energy Storage Systems 125(a)14 MECH-15A


Acceptance Tests Always Applied to Single Zone Rooftop Units

•  MECH-2A - Outdoor Air for CAV – Measured outside air within 10% of the values

listed on MECH-3C

•  MECH-3A - Constant Volume & Single-Zone Unitary – Verifies that sequence of operation is correct

•  Setup and setback works •  Fan turns off – unoccupied period •  When fan off – O/A damper closed •  No simultaneous heating and cooling


Acceptance Tests - Single Zone Rooftop Units – sometimes in order of likelihood •  MECH-5A - Economizer Controls

–  Only if the unit has an economizer •  MECH-6A - Demand Control Ventilation

–  Required for high density applications •  Retail (first floor) •  Auditoriums •  Schools are specifically exempt

•  MECH-4A - Air Distribution Ducts –  Duct leakage test –  Only if > 25% of duct surface area outdoors or in

ventilated attic (not plenum) –  Change-outs ducts not inc conditioned space


Acceptance Tests Always Applied to Variable Air Volume Systems

•  MECH-2A - Outdoor Air for VAV – Measured outside air within 10% of the values

listed on MECH-3C at high and low flowrate

•  MECH-7A Supply Fan VAV – Fan slows down at lower loads – For DDC to zone, duct pressure drops

•  MECH-5A - Economizer Controls – Systems over > 75,000 Btu/h required to have

an economizer


Direct Digital Control to the Zone

•  System has a central automated control that receives feedback from all zones – Allows pressure reset of variable flow fans or

pumps •  Pressure dropped until most open damper or coil

valve is almost full open. Thus all zones have enough pressure.

– Allows resetting of zone temperature in response to a utility signal (demand response)

– Allows adjusting outside air in response to CO2 level in zones


Acceptance Tests Frequently Applied to VAV Systems with DDC to the Zone •  MECH-11A Automatic

Demand Shed Control –  Setup in response to utility

signal

•  MECH-6A Demand Control Ventilation –  Required for high density

applications •  Retail (first floor) •  Auditoriums •  Exempted: Schools, healthcare,

social service


Acceptance Tests Usually Applied to Hydronic Systems •  MECH-8A - Valve Leakage Test

–  Check isolation valves on boilers and chillers

–  Test all valves on rest of system •  MECH-10A - Hydronic System

Variable Flow Control –  Under low coil load, fan speed

drops –  Under low coil load, system that

is DDC to zone, pressure drops •  MECH-9A - Supply Water

Temp. Reset –  Reset required only for systems

> 500,000 Btu/h. –  If system has controls, test

required


Compliance forms end in “–C”


5

VAV AHU 1 & 2 2 CHW System 1

CV RTU 1 to 5

Checks in red indicate tests that would always be done for these system types


What is an acceptable package of acceptance tests

•  All Acceptance Tests listed on MECH-1C are completed

•  All signature blocks legible and signed

•  All values filled in & specific to equipment –  Identical values for all tests indicate tests not

being conducted

•  All tests should be “Passed”


Changes in 2008

•  Revisions to MECH-1C Certificate of Compliance

•  New Field Inspection Checklist

•  New Installation Certificate (10-103(a)3A)

•  Reorganized Acceptance Test Forms (Certificates of Acceptance)

T24 2008 HVAC Forms


The not so fine print

•  Systems Acceptance. Before occupancy permit is granted …

•  … all control devices shall be certified as meeting the Acceptance Requirements

•  Systems Acceptance. Before occupancy permit is granted. All newly installed HVAC equipment must be tested using the Acceptance Requirements.

•  The MECH-1C form is not completed and is not to be accepted by the building department unless the correct boxes are checked.

•  The building inspector must receive the properly filled out and signed forms before the building can receive final occupancy.

•  Do you see a pattern??


New Field Inspection Checklist •  Filled out by designer or Title

24 documentation author (or automatically by compliance software)

•  Used by field inspector to help identify critical components

Title 24 2008


Installation Certificate

•  Completed by licensed person responsible for building construction or installation of the mechanical system

•  Certifies that installed system meets code requirements

Title 24 2008

There is no longer a MECH 1A Form!


Project information (typical)

Technician block (typical)

Reviewer block (typical)

Acceptance forms end in “-#A”


People Qualified to Certify Tests “Responsible Person”

•  California licensed engineer, or architect –  Eligible under Division 3 of the Business &

Professions Code ... to take responsibility for the scope of work

–  Mechanical and civil engineers

•  California licensed contractor


California Contractors typically eligible to take responsibility for acceptance tests •  A General Engineering Contractor •  B General Building Contractor •  C-4 Boiler, Hot Water Heating System Fitting Contractor •  C-20 Warm-air Heating, Ventilation & Air Conditioning Contractor •  C-36 Plumbing Contractor •  C-38 Refrigeration Contractor •  C-43 Sheet Metal Contractor •  D-62 Air and Water Balancing •  C-10 Electrical Contractor (controls) •  C-7 Low Voltage Systems Contractor (controls)

•  Other contractors with related classifications


Construction inspection (typical)

Functional Testing block (typical)


Test summary (Typical)


Completed acceptance tests are a condition of the Certificate of Occupancy

•  Late installation of a given piece of equipment is no excuse

•  All other equipment can be tested and a conditional permit granted for the late piece of equipment


Simple Spot Tests – Summer Economizer

•  Have contractor place all AC in cooling mode in early morning – All economizers should be open

•  Have contractor place in heating mode – All economizers should be closed

•  Have contractor place systems back in cooling mode – All economizers should close when it is hot

out


Simple spot tests VAV system – summer

•  Have contractor set cooling setpoint low – Fan speed should increase – listen or look at

VFD output

•  Have contractor set cooling setpoint high – Fan speed should decrease


Minimum Outdoor Ventilation Air Acceptance MECH-2A Appendix NA 7.5.1


Why is minimum outside air important

•  Too little O/A – sick building syndrome – Often too little O/A at low flow for VAV

systems

•  Too much O/A – huge energy penalty – Hot summer day - 3 tons extra cooling for

each 1,000 cfm excess outside air.

•  Without adjusted O/A – easily 100% excess outside air


Outside air dampers

•  When in heating mode or in cooling mode where bringing outside air would increase load on building…

•  ….outside air dampers are set or controlled to allow the minimum outside air needed to protect health and dispel normal odors.


Purpose of Outdoor Air Acc. Test

•  Verification of minimum OutSide Air (OSA) as scheduled on plans

•  Verification that minimum OSA is provided throughout the range of operation in a VAV system and at design for CV systems

•  Measured CFM of minimum outside air at min flow and full flow must be within 10% of design CFM on MECH-3C


Design Minimum Outside Air MECH-3C VAV-O = office space, VAV-A = assembly space, Min O/A in Column I

VAV-O 1,000 0.15 150 5 75 150 160 350 400 400 300 N/A

VAV-A 1,000 0.15 150 34 510 510 510 1,200 400 1,200 550 N/A

Totals 39 660 670 0 Min O/A for MECH-2A

67 x 0.5 = 34


Fixed Minimum OA Damper Position only allowed for constant volume systems

Outdoor Air Intake

Return Air

Minimum Signal Pot.

Signal from SAT Controller

For VAV systems does NOT WORK since mixed air plenum pressure varies!! Outdoor

air flow will vary proportional to supply air flow


Test Procedure CV System

1.  Disable economizer (if applicable) 2.  Disable DCV (if applicable) 3.  Measure and record OSA 4.  Restore boxes, economizer and DCV

controls

Setup

Test

Clean up


How to Disable an Economizer

•  Drop high-limit control setpoint below current OA temperature or enthalpy (all controls), or

•  Raise OA temperature or enthalpy reading above high limit control setpoint (DDC controls), or

•  Disable economizer control block (DDC controls)


How to Disable and Engage DCV Controls

•  Disable DCV – Raise CO2 setpoint significantly above current

CO2 reading (all controls)

•  Engage DCV – Lower CO2 setpoint to lowest possible

setpoint (all controls)


How to Measure OSA

•  AFMS (air flow monitoring station) –  If part of the system

•  Calibrated damper (if part of the system)

•  Traverse of OSA louver/duct

•  Traverse of SA and RA ducts (differential)

•  For each test OSA must be +/-10% of design

•  Note: on small packaged units you might have to provide a temporary sheet metal hood on the OSA intake to get a good reading


Construction Inspection

•  Calibration of AFMS or calibrated damper (if part of the system)

•  Verify that there is a provision for dynamic control of OSA (if VAV)

•  Verify that there is a provision for minimum OSA (if CV)


VAV Acceptable O/A Control Dual Minimum

•  Minimum damper position is set proportionally based on fan speed between setpoints determined when the fan is at full speed and minimum speed

•  Low cost

•  Affected by wind, stack effect, filter loading


Example Method of Dynamic OSA Control: Injection Fan


Outdoor Air Intake

Return Air

Injection Fan w/ Discharge Damper


Outdoor Air Intake

Return Air


Example Method of Dynamic OSA Control: Fixed Damper with DP control

∆P correlated to flow for fixed orifice Can be 1 section or

entire OA damper


Test Procedure VAV System

1.  Disable economizer (if applicable) 2.  Disable DCV (if applicable) 3.  Drive all boxes to minimum airflow 4.  Measure and record OSA 5.  Drive all boxes to design airflow 6.  Measure and record OSA 7.  Restore boxes, economizer and DCV controls 8.  System passes if measured OSA in steps 4 & 6

are within 10% of design OSA Combine tests to save time and $$

–  MECH-2A full airflow test with DCV disabled –  MECH-6A. full airflow test with DCV enabled

Setup

Test 1

Test 2

Clean up


How to Drive VAV Boxes Open

•  Set zone cooling temperature setpoint below the current zone temperature (all controls)

•  Override the VAV box airflow setpoint (DDC controls)

•  With DDC controls you might want to specify preset functions to drive all boxes to design airflow and minimum airflow to speed up the tests

•  Note: if you override the VAV box damper you may provide more than the design maximum airflow


How to Drive System to Minimum Airflow

•  Set zone cooling temperature setpoint above the current zone temperature (all controls)

•  Override the VAV box control airflow setpoint (DDC controls, could be preset)

•  Manually slow down fan until airflow is ~30% of design airflow (all controls, requires AFMS or duct traverse)


Project information

(typical)

Technician block

(typical)

Reviewer block

(typical)


Title 24 2008

Construction inspection

(typical)

Testing block (typical)

1,910 2,000

3.2 mins

92.5

95.5

1,850 2,000

3 mins

AH 1 2nd Floor Offices

Project XYC, Somewhere, California


Test summary (Typical)

AH 1 2nd Floor Offices

Project XYC, Somewhere, California


Reasons to Reject the MECH-2A

•  Signatures or names are missing for technician or reviewer

•  Ratio of measured flowrate to design outside air flow rate (Percent OSA) – >110%

– <90%

•  Suspicious if all tests: – Measured airflow equal to design airflow rate


Packaged HVAC Controls MECH-3A


Purpose

•  Check thermostat, setpoints and scheduling controls

•  Verify that heating, economizer and cooling are properly sequenced

•  Verify operation in occupied and unoccupied modes


MECH-3A Functional Tests

•  Simulate various operating modes –  Heating load occupied, no-load occupied, heating

load unoccupied, no load unoccupied, etc. –  Each condition is a column on the table

•  Check for various HVAC unit responses –  Different responses represented by each row –  Areas grayed out are incorrect responses –  Areas with check boxes are correct responses

•  Test and fix until under each operating mode only responses are those indicated by check box


Occupied Mode Test Procedure

1.  Heating –  Supply fan operates continuously –  OSA is provided –  No cooling occurs –  Verify that all heating stages work

2.  Dead Band –  Supply fan operates continuously –  OSA is provided –  No heating or cooling occurs

3.  Cooling –  Supply fan operates continuously –  OSA is provided –  No heating occurs –  Verify that all cooling stages work

Note the cooling test is repeated under economizer acceptance


How to drive the unit into heating, cooling or deadband •  Cooling

–  Move thermostat cooling setpoint below the current room temperature

•  Dead Band –  Move the thermostat cooling setpoint above the

current room temperature, and –  Move the thermostat heating setpoint below the

current room temperature •  Heating

–  Move the thermostat heating setpoint above the current room temperature


Unoccupied Mode Test Procedure

4.  Heating –  Supply fan cycles on with call for heating (and off when satisfied) –  OSA is closed or cycles with supply fan –  No cooling occurs

5.  Dead Band –  Supply fan is off –  OSA damper is closed –  No heating or cooling occurs

6.  Cooling –  Supply fan cycles on with call for heating (and off when satisfied) –  OSA is closed or cycles with supply fan –  No heating occurs

Again, the cooling test is repeated under economizer acceptance


How to move the unit into “unoccupied” mode

•  Adjust the schedule so that the unit is scheduled off at the current time, or

•  Reset the current time so that it is outside of the scheduled occupied period


Override Mode Test Procedure

7. Enable after hours override –  System goes to “occupied” mode

–  System returns to “unoccupied” mode after timed delay

8. Return system to normal operation –  Reset all setpoints

–  Remove any jumpers


How to activate the after-hours override

•  Put the unit into “unoccupied” mode (see previous slide)

•  Push the after-hours button on the thermostat


Air-Side Economizer MECH-5A


Purpose

•  Check economizer installation and provision for exhaust or relief

•  Test economizer operation

•  When a call for cooling and it is cool outside the economizer brings in outside air

•  Other times min O/A


Overview

•  References –  Standard Sections §144(e) and §125(a)4

–  Form MECH-5A

–  Non-Residential Appendix NA 7.5.4

–  Nonresidential Compliance Manual 10.6.10

•  Scope –  All new systems with air-side economizers

–  No functional testing required if economizer is factory installed and certified operational

•  None certified currently


High Limit Switch


Economizer Functional Testing

Step 1: Disable demand control ventilation (DCV) systems (if applicable) Step 2: Enable the economizer and simulate a cooling demand

–  Economizer damper is 100 percent open and return air damper is 100 percent closed.

–  For systems > 75,000 Btu/h economizer is integrated •  100 % open when the cooling demand can no longer be met by the economizer alone.

–  All applicable fans and dampers operate as intended to maintain building pressure.

–  The unit heating is disabled. Step 3: Disable the economizer and simulate a cooling demand.

–  Economizer damper closes to its minimum position. –  All applicable fans and dampers operate as intended to maintain building

pressure. –  The unit heating is disabled

Step 4: Simulate a heating demand and set the economizer so that it is capable of operating (i.e. actual outdoor air conditions are below lockout setpoint).

–  The economizer is at minimum position Step 5: Restore DCV systems and remove all system overrides


How to Disable an Economizer

•  Drop high-limit control setpoint below current OA temperature or enthalpy (all controls), or

•  Raise OA temperature or enthalpy reading above high limit control setpoint (DDC controls), or

•  Disable economizer control block (DDC controls)

•  Do the opposite to enable economizer


VAV Supply Air Acceptance Test MECH-7A

Drawing courtesy of Steven Taylor


Purpose

•  Check calibration and setpoint of pressure sensor for VAV systems

•  Check stability of control on VAV systems at full and part load

•  Make sure fan speed slows with reduced load, supply air pressure does not rise

•  For DDC to zone system, system air pressure drops at reduced load


Overview

•  References –  Standard Sections §144(c)2B, C & D and §125(a)6

–  Non-Residential Appendix 7.5.6

–  Nonresidential Compliance Manual 10.6.14

•  Scope –  New VAV fans greater than or equal to 10 hp

–  Both prescriptive and performance approach


Construction Inspection - Verify

•  Discharge static pressure sensors are either factory calibrated or field-calibrated.

•  The static pressure location, setpoint, and reset control meets the requirements of §144(c)2C and §144(c)2D.

–  Sensor Location so set point < 1/3 the total design static P (i.e. near the end of the duct)

•  except for DDC to zone systems w/ pressure reset

–  If located below major duct splits, sensors in each major branch, take lowest value for control

–  DDC to Zone, Set Point Reset. •  pressure set point based on the zone w/ most need •  zone damper needing most pressure is nearly wide open.


Construction Inspection


Test Procedure

You may have to disable SA temperature reset during this test to prevent unwanted flow fluctuations

1.  Drive boxes to achieve design airflow (refer to min OSA test for how to do this)

2.  Record measured SP (must be +/- 10% of setpoint)

3.  Note if fan speed stabilizes within 5 minutes


Test Procedure

4.  Drive boxes to achieve minimum airflow (refer to min OSA test for how to do this)

5.  Record measured duct static pressure (must be +/- 10% of setpoint)

6.  For DDC to zone systems, pressure setpoint must be reduced

7.  Note if fan speed stabilizes within 5 minutes


Functional Performance Testing


Demand Control Ventilation (DCV) MECH-6A


Demand Control Ventilation Requirements (§121(c)4)

•  Where DCV is applied, it must meet the following: –  One sensor for each space that meets the criteria of 121(c)3B

–  Sensor must be CO2

–  Sensor must be located in the breathing zone between 3’ and 6’ AFF or at the anticipated level of the occupant’s heads

–  Maintain setpoint of 600ppm + OSA ppm •  400 PPM default or •  dynamically measured

–  No greater than design ventilation @ 15 cfm/person

–  No less than ventilation from Table 121-A (cfm/ft2)

–  Design ventilation for spaces without DCV


Do Return CO2 Sensors Work?

Return is diluted by other Zones and does not track the critical zone

No. Separate sensors are needed in each high density space


Purpose

•  Check DCV calibration and installation

•  Test DCV at: – High CO2 levels

– Low CO2 levels


Related Tests

•  NA 7.5.1 Outdoor Air Acceptance

•  NA 7.5.4 (Air-Side) Economizer Acceptance

This test should be combined with minimum OSA and economizer acceptance tests to reduce time and costs


DCV Test Procedure

•  Disable economizer controls •  Measure CO2 concentration

–  If dynamic control < 600 ppm above ambient concentration –  Default ambient concentration 400 ppm, indoor air < 1,000 ppm

•  Step 1:Simulate a signal at or slightly above the CO2 concentration setpoint required by §121(c)4C. Verify and document the following:

–  For single zone units, outdoor air damper modulates open to satisfy the total ventilation air called for in the Certificate of Compliance.

–  For multiple zone units, either outdoor air damper or zone damper modulate open to satisfy the zone ventilation requirements.

•  Not required to have cfm greater than MECH-3C column I (design ventilation air cfm)

•  Step 2: Simulate signal well below the CO2 setpoint. Verify : –  For single zone units, outdoor air damper modulates to the design minimum

value. –  For multiple zone units, either outdoor air damper or zone damper modulate less

open to satisfy the reduced zone ventilation requirements. •  CFM must be at least as much as MECH-3C Column D (Min CFM by Area) for DCV

controlled zone + MECH-3C column I (design ventilation air cfm) for uncontrolled zones

•  Step 3: Restore economizer controls and remove all system overrides initiated during the test.


Overriding CO2 Controls

•  To simulate high demand you need to decrease the sensor setpoint

•  To simulate low demand you need to increase the sensor setpoint

•  Best accuracy results from using calibrated gas


Default is 400 ppm


Duct Sealing Air Distribution Systems

MECH-4A


MECH-4-A Air Distribution §144(k)

•  Small (<5,000 sf) CV systems only

•  When > 25% of duct surface is outdoors or in unconditioned space

•  Place greater than 75% of ducts under insulated roof – test not needed

•  Ducts must be tested for duct leakage …. and verified as sealed by a HERS rater


MECH-4-A Construction Inspection

•  Drawbands –  Stainless steel worm drive or

–  UV resistant nylon duct ties

•  Duct leakage tests performed before access is blocked

•  Duct tape not used unless with drawbands and mastic

•  R-8 insulation

•  Outdoor insulation protected from damage


MECH-4A Calculated supply fan flow

•  Rated flow from capacity –  400 cfm/ton

–  21.7 cfm/kBtuh heating only systems


MECH4-A Leakage Test New Construction

•  Seal all diffusers

•  Pressurize system to 25 Pa (0.1 in WC) with fan with calibrated orifice (duct blaster)

•  Measured leakage no greater than 6% of rated flow

•  Likely conducted by HVAC contractor

•  Verified by HERS rater


MECH-4-A Duct testing


MECH-4A Duct Testing Results New Construction or Alterations

Alterations

New


MECH-4-A Duct Sealing on Retrofits §144(k), 149(b)1D&E Applies to small CV system with ducts outside or in

unconditioned spaces when: –  Ducts replaced –  HVAC system is replaced or major repair (new

compressor, new coil etc.) Existing duct leakage

–  ≤15% of rated supply flow –  >60% reduction of leakage prior to sealing ducts with

all visible leaks sealed –  Can’t get at the ducts and all visible leaks are sealed

as certified by a HERS rater •  Exceptions

–  Asbestos –  Existing ducts that were previously certified


HERS Rater Sampling Test Validation

•  All systems must best tested by person conducting acceptance tests

•  Independent HERS rater verifies results through sampled re-testing of systems: –  Verify the first system tested –  Verify one out of the each group of 7 tested

•  If that unit fails the test, •  test a second unit in the group of 7 •  if that fails test the other 5 in the group of 7

–  Certify ALL of the tests made by the contractor –  Enter all tests into the HERS database

•  New groups of 7 applies to each new construction project (but not for retrofit)


Automatic Demand Shed Controls


Automatic Demand Shed Controls (122(h))

•  For systems with DDC to the zone: –  Ability to reset thermostat setpoint up to 4°F on all “non-critical”

zones through real or virtual DI.

–  System needs an adjustable rate of change for reset

•  Shown by LBNL and Purdue to reduce on-peak demand by over 30%.

•  Supported by ASHRAE Standard 55 (Table 5.2.5.2).

6.0°F 5.0°F 4.0°F 3.0°F 2.0°F Maximum Operative Temperature Change Allowed

4 h 2 h 1 h 1/2 h 1/4 h Time Period

6.0°F 5.0°F 4.0°F 3.0°F 2.0°F Maximum Operative Temperature Change Allowed

4 h 2 h 1 h 1/2 h 1/4 h Time Period

All New!


Overview

•  References – Standard Sections §122(b)4, §122(h) and

§125(a)10 – Non-Residential Appendix NA 7.5.10 – Nonresidential Compliance Manual 10.6.19

•  Scope – New DDC Zone Controls


Purpose

•  To make sure that the demand shed controls are programmed and work when engaged

•  Demand shed controls gives the owner the opportunity to temporarily turn up t-stats in all non-critical areas 4F a few hours per year. – Utility financial incentives – Less likely to have a black-out


Automatic demand shed controls

•  NA7.5.10.1 Construction Inspection •  Prior to Acceptance Testing, verify and document the

following: –  That the EMCS interface enables activation of the central

demand shed controls.

•  NA7.5.10.2 Functional Testing •  Step 1: Engage the global demand shed system. Verify :

–  Cooling setpoint in non-critical spaces increases by the proper amount.

–  Cooling setpoints in critical spaces do not change.

•  Step 2: Disengage the global demand shed system. Verify : –  Cooling setpoint in non-critical spaces return to their original

values. –  Cooling setpoint in critical spaces do not change.


Beyond Scope for Today

ACM Section and Test Standard Section NA 7.5.1.11 FDD for Packaged DX Systems 125(a)11 NA 7.5.1.12 FDD for AHUS and Zone Terminal Units 125(a)12 NA 7.5.1.13 Distributed Energy Storage DX AC Systems 125(a)13 NA 7.5.1.14 Thermal Energy Storage Systems 125(a)14

These tests are documented in the Non-Residential Appendices and Non-Residential Compliance Manual. They are only required when you seek a compliance credit.


Summary

•  Acceptance tests assure that design intent for energy savings is executed

•  All heating and cooling systems have at least one associated acceptance test

•  The designer identifies which tests get applied to which equipment on the MECH-1-C form

•  Plans examiner reviews MECH-1C form to assure all equipment has applicable tests specified –  Compliance forms are rejected and returned to applicant if all

applicable HVAC systems and tests are not called out •  Fully COMPLETED acceptance test forms with all

systems PASSING must be given to inspector before building receives Certificate of Occupancy. –  Schedule a challenge test if results are suspicious


Sample Questions

•  Which compliance form lists all acceptance tests that must be conducted?

•  Who can be a “responsible person” for the acceptance tests?

•  Are acceptance tests a requirement for a certificate of occupancy?

•  Which acceptance test requires a third party HERS verification?

•  Are any tests valid without 3d party verification? •  What is done if a system does not pass an

acceptance test?


More questions

•  What tests are always required on constant air volume systems?

•  What tests are always required of VAV?

•  What tests are usually required of VAV systems with DDC to the zone?


Outdoor Air Acceptance Test Questions

•  Which compliance form contains the design ventilation air information?

•  Measured ventilation air cfm must be within what percentage of design ventilation air cfm?

a)  5%, b) 10%, c) 30%, d)50%

•  For VAV, variable air volume, systems outside air must be measured at design (full) flow and at what other supply air flowrate?


Packaged A/C Acceptance Test Questions

•  Select all true answers below

When is supply fan on during occupied hrs: a) Heating call, b) Cooling call, c) No call for

either heating or cooling When is supply fan on during unoccupied hrs:

a)  Heating call, b) Cooling call, c) No call for either heating or cooling

•  When is the outside air damper completely closed?


Air-side Economizer Test Questions

•  True or False – Economizer open when call for cooling and

outside air temp is below high limit setpoint – Economizer is open when call for heating and

outside air temp is below high limit setpoint – Economizer closed when call for cooling and

outside air temp is above high limit setpoint – Construction inspection not required for

factory installed economizer w/ CEC certification.


Resources – 2008 Standard

•  Energy Efficiency Hotline – E-mail: [email protected]

– Phone: 916-654-5106 or

– Phone: 1-800-772-3300 (toll free in Calif.)


Acknowledgements

•  California Commissioning Collaborative

•  Pacific Gas & Electric Company – Codes & Standards Program

•  California Energy Commission – Tav Commins, Project Manager

•  Mark Hydeman, Taylor Engineering

•  Jon McHugh, McHugh Energy Consultants

2008 title 24 nonresidential hvac acceptance testing for...

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