13.91 NA 7.6.3 Demand Responsive Controls Acceptance

Demand Responsive Controls Acceptance

Use Form NRCA-LTI-04-A

Purpose of the Test

The purpose of the test is to ensure that the demand responsive control is capable of reducing the power consumption of the lighting system to no more than 85% of full power (or, if the lighting system is “tuned” to a lower output, 85% of the tuned output). The test also confirms that the lighting system produced a reasonably uniform level of light during a demand response event.

Benefits of the Test

With a fully functional demand responsive lighting system, the building owner or operator can save money by reducing their lighting power consumption during periods of high power cost and/or periods of grid instability. As well as saving money, this also improves the reliability of the power grid for all consumers.

Instrumentation

This test requires EITHER an illuminance meter or a power meter (with a current transformer and voltmeter). Alternatively, if the lighting system has an inbuilt method of measuring (not estimating) the lighting power being consumed, this inbuilt measurement may be used instead.

Test Conditions

All luminaires are wired and powered.

Put the lighting system into a state that is representative of typical daytime use.

Identify the input(s) to the lighting system that are intended to function as demand responsive controls. These will be 'listed in column H of the lighting control schedule on the Lighting Certificate of Compliance, NRCC-LTI-02-E.

If possible, take measurements in non-daylit areas, to make the calculations loss prone to error.

Estimated Time to Complete

Construction Inspection: 0.25 to 0.5 hours

Equipment Test: 0.5 to 1 hours (depending on the number of controlled luminaires)

Acceptance Criteria

The demand response system(s) are able to receive and respond to a suitable demand response signal from a utility or other provider, or from another building system. Note that the functional test does not actually require a demand response signal to be given; it only requires the tester to verify that the system is capable of receiving and responding.

The demand response system is capable of reducing the power consumed by the lighting system to no more than 85% of full output, while preserving adequate uniformity in task areas.

Potential Issues and Cautions

If using Method 1 (Illuminance Measurement), find a way to mark the exact locations in which the illuminance measurements were made, because even slightly differences in the location of the illuminance meter, or the angle at which it is held, can significantly affect the readings. If possible, take readings away from shadowed areas.

If illuminance measurements or power measurements are taken in daylit areas with photocontrols, the values can change very significantly in just a few minutes, due to changes in daylight availability. Try to take measurements as far from sources of daylight as possible.

• The demand responsive control is capable of receiving a demand response signal directly or indirectly through another device and that it complies with the requirements in Section 130.5(e).

• §130.5(e): Demand responsive controls and equipment shall be capable of receiving and automatically responding to at least one standards based messaging protocol which enables demand response after receiving a demand response signal.

• Definition from §101: DEMAND RESPONSE SIGNAL is a signal sent by the local utility, Independent System Operator (ISO), or designated curtailment service provider or aggregator, to a customer, indicating a price or a request to modify electricity consumption, for a limited time period.

• “Capable of receiving”. The demand response control must have an electronic input that can carry a messaging protocol, as described below. This does not need to be a dedicated input; it can carry other signals in addition to the demand response signal. In practice, this could be an EMCS connection.

• “Automatically responding to”. The control must be capable of responding to the demand response signal automatically, without human assistance or intervention.

• “Standards based messaging protocol”. The term ‘protocol’ refers to a format for conveying messages, so the input to the demand responsive control must be able to convey different messages. It must be more than just a contact closure or similar binary input.

• If the demand response signal is received from another device (such as an EMCS), that system must itself be capable of receiving a demand response signal from a utility meter or other external source.

• This means that the EMCS or other system must meet the same requirements given above for a demand responsive control. It must be capable of receiving a standards-based protocol, and the lighting system must respond automatically.

The functional test ensures that the demand responsive control can set the lighting to a lower-power condition, in line with the requirements set out in Title 24 Part 6, Joint Appendix NA7.

• Reduce the lighting power to no more than 85% of “full output”. Full output is defined in the field test as being the output of the lighting system when all manual switches are on, but some luminaires may be dimmed or switched below their maximum output because they are “tuned” or because they are controlled by automatic systems such as photocontrols and vacancy sensors.

• Ensure that the visual conditions for occupants under the demand response condition are still comfortable, and allow them to work uninterrupted during the event. When the demand responsive control is activated, the output of the lighting system must still be at least half of its output in the “full output” condition.

• Ensure that light levels do not go below any preset minimums that have been determined, for instance, by facilities managers. This is the purpose of the “minimum output test”.

If the demand responsive control has a “test mode” that allows the demand response condition to be simulated, this is adequate for the Acceptance Test; the tester does not have to confirm that the demand responsive control responds to a real signal.

However, if the control does not have a test mode, then the input signal must be simulated. In some cases this may be simple, for instance if the control responds to a contact closure. However, if the control can only be tested by providing it with a specific demand response signal, then that signal must be generated during the Acceptance Test.

Using the illuminance measurement method (Method 1) requires the tester to take two illuminance measurements at the same location several minutes apart. This process can incur a high degree of error, which can be minimized by observing these precautions::

• Find easily-repeatable locations. Leave a marker such as a sticky note to record the exact location of the illuminance meter , or put the meter in a clearly defined location such as a join between cubicle partitions.

• Avoid shadows. Shadows can move in between measurements if they’re caused by daylight, and if the edge of the shadow falls across the illuminance meter’s sensor, the reading will be very unreliable.

• Avoid daylit areas. Daylight can vary in brightness significantly in the course of just a few seconds, so place the illuminance meter as far as possible from windows, ideally not in direct line of sight.

• Hold the meter at arm’s length, or squat below the level of the sensor. Many illuminance meters require a button to be held in while taking measurements, and your body and head will shade the sensor. Minimize the error caused by this effect by holding the meter at arm’s length or by squatting down to remove your head and body from the path of the incoming light.

The area-weighting calculations required by the functional test are simple, though the equation on the forms is complicated. An example is given below.

The following measurements were taken in a building, for the full output test. For convenience, all the daylight measurements are zero.

Lines a and c have been omitted for clarity		Space number
		1	2	3
b.	Take one illuminance measurement at a representative location in each space, using an illuminance meter.	30 fc	35 fc	40 fc
d.	Take one illuminance measurement at the same locations as above, with the electric lighting system in the demand response condition.	15 fc	20 fc	40 fc
e.	Turn off the electric lighting and measure the daylighting at the same location (if present)	0 fc	0 fc	0 fc
f.	Calculate the reduction in illuminance in the demand response condition, compared with the design full output condition. [((line b - line e)- (line d – line e)) /(line b - line e)]	50%	43%	0%
g.	Note the area of each controlled space	2000 sf	800 sf	1300 sf
h.	The area-weighted reduction must be at least 0.15 (15%) but must not reduce the combined illuminance from electric light and daylight to less than 50% of the design illuminance in any individual space.	{(50%x2000) + (43%x800) + (0%x1300)} = 2000 + 800 + 1300 = 8.3%……so the space complies.