Acceptance testing must be tailored for each specific design, job site, and climatic conditions. While the steps for conducting each test and the acceptance criteria remain consistent, the application of the tests to a particular site may vary. The following section discusses some of the known issues that occur when the acceptance tests are applied to a project.
General Issues- Envelope
Important aspects to the Fenestration Acceptance requirements are:
•Verify thermal performance (U-factor, SHGC and VT) of each specified fenestration product matches the fenestration certificate, building plans, energy compliance documentation, and that each product matches purchase order or receipt.
•If the to be installed fenestration thermal performance is equal or better than the specified or 'listed on the energy documentation then no further re-compliance is required.
•If the to be installed fenestration is less than the energy documentation then re-compliance is required. Installing less efficient fenestration can increase the building’s cooling load and change the overall energy use of the building.
•If using the Performance Approach then the weighted average thermal performance per orientation can be used as long it’s equal or better than the specified values as noted above; otherwise, re-compliance is required.
General Issues – Mechanical Combining Tests to Reduce Testing Costs
Many of the acceptance tests overlap in terms of activities. For example, both Reference Nonresidential Appendix NA7.5.1.1 Ventilation systems for Variable Air and Constant Volume Systems Acceptance and NA7.5.6 Supply Fan Variable Flow Controls (FVC) Acceptance require that the zone controls be overridden to force the system into full design flow and low flow conditions. Since the bulk of the time for either test is the process of driving the zone controls (e.g. VAV boxes) into a set position it makes sense to combine these two tests: performing the superset of activities with the boxes at both design and part-load conditions. There are a number of places where combining tests will save time. These are summarized here and described again in the individual test descriptions.
Tests that require override of zone controls:
•NA7.5.1.1 Ventilation systems for Variable Air Volume Systems Acceptance and
•NA7.5.6 Supply Fan Variable Flow Controls Acceptance.
Tests that require override of the OSA damper:
•NA7.5.1.1 Variable Air Volume Systems Outdoor Air Acceptance (or NA7.5.1.2 Constant Volume Systems Outdoor Air Acceptance),
•NA7.5.4 Air Economizer Controls Acceptance,
•NA7.5.5 Demand Controlled Ventilation Systems Acceptance, and
•NA7.5.11 Fault Detection and Diagnostics (FDD) for Packaged Direct-Expansion Units
Tests that require changing the unit mode of operation:
•NA7.5.2 Constant Volume, Single-zone, Unitary Air Conditioner and Heat Pumps Systems Acceptance and
•NA7.5.4 Air Economizer Controls Acceptance.
Tests that require deadheading the circulation pump and overriding control valves:
•NA7.5.7 Valve Leakage Tests and
•NA7.5.9 Hydronic System Variable Flow Controls Acceptance.
Internal control delays
Be aware of the potential for delays programmed into many control sequences. The purpose of delays is to prevent the system from controlling too rapidly and becoming unstable. With delays between 5 to 30 minutes, the acceptance testing can be prolonged considerably.
Examples include the normal time that it takes to stroke a damper (typically several minutes end to end) and anti-recycle timers on refrigerant compressors (typically on the order of 5 to 15 minutes).
Initial conditions
Each test instructs the contractor to return the systems to normal operating condition based on the initial schedules, setpoints, and control parameters. These initial settings shall be recorded prior to initiating the testing process.
Obtain correct control sequences before testing
It is essential to know exactly what the control sequences are before testing begins. Otherwise, the contractor will not be able to customize the test to the particular systems or verify that the systems work as intended. In many cases, the testing will be performed in conjunction with the controls contractor. Also many of these tests can be performed as part of the equipment/system start-up process.
Internal electronic controls are usually documented in the equipment O&M 'manual.
With pneumatic controls, you need to review the control drawings to ascertain how the system is being controlled.
With DDC controls, it is best to review the control programming that is currently loaded in the controllers. It is important to note that the actual control logic is often different from the sequences on the design plans and specifications for a number of reasons including:
•Poorly written or incomplete sequences on the design drawings.
•Standard practices by the installing EMCS contractor.
•Issues that arose in the field during control system start-up and commissioning.
Functional Testing based on incorrect sequences will not necessarily yield a valid result.
Estimated Time to Complete
To give the full picture to contractors, the test summaries below (“At-A-Glance”) include estimates of the time to complete construction observation as well as functional testing on each system. These estimates are made for a specific test on a specific system and need to be aggregated to estimate the total time for completion on all systems associated with the entire building. These estimates need to be used with caution; times will vary depending on a number of factors including the complexity of the controls, the number of control zones, the number of similar tests and other issues. Expect that the first time a test is performed it will take longer. Subsequent tests will take less time as the tester becomes more experienced and familiar with the test.