Helpful? 0

Do wireless switches save energy?

I know zip about electricity. Consider two homes almost exactly the same, both conditioned by heat pumps (to drop gas out of the equation). But, one has traditional electrical wiring/conduit to all loads and switches. And the other only has wiring and conduit to the loads but no wiring and conduit from loads to switches because the switches generate radio frequencies and are self-powered (flipping them or ambient room light solar generates enough power to send the signal). Considering the whole electrical load (including heating/cooling in Northern Zone 5a), which home uses more energy?

On one hand, proponents of wireless switches point out their house has less conduit to transfer unwanted temperatures around either through conduction or air simply blowing through them, so the house is automatically more air tight . Furthermore, sealing is not always done perfectly, so the fewer penetrations the better (for instance, wiring coming into switch boxes does not have to be sealed because there is none). Also, there are LEED points for wireless switches.

On the other hand, another layperson pointed out that the receiver for the RF signal is wired into the wiring near the load it controls and, I and he assume, uses a small amount of electricity all day long to listen for the signal from the switch that controls it. Now consider a whole house full of these vampire loads (this is a link to one of the most commonly used types of receivers but my untrained eye doesn't see a power consumption spec... http://www.illumra.com/Products/Receivers/E3R-R12-3HOBP_3-wire_copy.html ).

Anyone have a feeling for gain in thermal efficiencies (reflected in the electricity the heat pump uses) due to a better sealed house vs. these vampire electrical loads I'm assuming are there (or other considerations)? Thanks.

Asked by Gordon B
Posted Mon, 05/19/2014 - 12:18
Edited Mon, 05/19/2014 - 15:50

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6 Answers

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1.
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I would not choose the wireless switch option for the following reasons:
1. Reliability, a power surge by a nearby thunderstorm will destroy ALL the wireless switches!
2. Expense, The cost of the wireless controls are significantly more than conventional switches and wiring.
3. The electricity used difference will be extremely small and most likely the conventional switch system will in fact use less power, both due to the fact that mechanical switches have lower on state losses than the best of electronic switches with the switch loss being far greater than the wire loss that longer wires to accommodate conventional switches might cause in addition to the "phantom" load already mentioned.
4. With proper sealing of wires through the "primary air barrier" the thermal losses of both systems are both small and equal.

Answered by Jerry Liebler
Posted Mon, 05/19/2014 - 15:23

2.
Helpful? 0

Thanks Jerry. @ Jerry or others... I'm not familiar with "on state losses." Does this mean that after the receiver for the wireless switch has been turned to the "on" position that it leaks more electricity than a conventional wired switch in the "on" position?

Answered by Gordon B
Posted Mon, 05/19/2014 - 15:44

3.
Helpful? 0

Gordon,
Yes! There are several types of solid state power switches but all of them have significant "on state" losses which typically waste, as heat, about 1% of the power being passed. OTH relays and mechanical switches rarely have "on state" losses greater than 1 in a million.

Answered by Jerry Liebler
Posted Mon, 05/19/2014 - 16:59

4.
Helpful? 0

Thanks Jerry! Good food for thought. One of my concerns is that I'm not fully convinced that air sealing is always done well or, even if done well initially, last over the years (this concern arises partly from reading this site).

Relative to "on state losses," let's assume a smart home saves energy overall and that thus both homes are "smart." Doesn't this drop the "on state" losses out of the equation because both buildings would be experiencing them (won't the smart switches on the switch legs of the building with wired switches be solid state and thus lose about the same amount of electricity while they are on as the receivers for the wireless switches in the other home while those receivers are switched on?)?

Gordon

Answered by Gordon B
Posted Tue, 05/20/2014 - 10:27
Edited Tue, 05/20/2014 - 11:11.

5.
Helpful? 0

Gordon,
If the issue is air sealing then you can avoid problems with electrical penetrations by locating the air barrier away from the interior of you building envelope. Even with conventional walls, losses from well sealed electrical penetrations typically are much less than those found at framing intersections and at plumbing penetrations.

Answered by Malcolm Taylor
Posted Tue, 05/20/2014 - 11:38

6.
Helpful? 0

This question is using more energy than the questioned.

Answered by aj builder, Upstate NY Zone 6a
Posted Tue, 05/20/2014 - 23:27

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