Saturday, January 2, 2016

Can Light Replacement Math

I challenge low ambitions for saving of energy in residential lighting, in current rules, 2015 International Energy Conservation Code, IECC, Chapter 4 :

R404.1 Lighting equipment (Mandatory).
Not less than 75% of the lamps in permanently installed lighting fixtures shall be high-efficacy lamps or not less than 75% of the permanently installed lighting fixtures shall contain only high-efficacy lamps.
Exception: Low voltage lighting.

Point source CFLs and other line-source fluorescent lamps are offered as these "high-efficacy lamps," as seen another 2015 IECC statement, Chapter 2, General Definitions :

HIGH-EFFICACY LAMPS Compact fluorescent lamps, T-8 or smaller diameter linear fluorescent lamps, or lamps with a minimum efficacy of:

60 lumens per watt for lamps over 40 watts;
50 lumens per watt for lamps over 15 watts to 40 watts; and
40 lumens per watt for lamps 15 watts or less.

These limits mean nothing for residential LED lights, usually less than 15 watts, and efficacy better than 50 lumens per watt. Limits are in ignorance about usefulness of silly point-source LEDs that fill our stores. About half of the lumens of point source and linear lamps are wasted, not at all contributing to task illumination, but perhaps coloring walls and ceilings. The lumens per watt of point and line sources must be reduced by half, roughly, for comparison with directional light broadly aimed at a task, as with large beam angle downlighting. A point-source LED bulb at 50 lumens per watt is useless for task illumination, and is not high-efficacy.

The US Department of Energy seems to be the author of these rules, and does offer improvement for 2018. Here are seven residential energy submittals by US DOE, for 2018 IECC: 
This is claimed for R-5, High-Efficacy Lighting (R202)
Redefine "high-efficacy" to acknowledge the marketplace penetration of LED lamp technologies. The availability of LED lamps is growing rapidly and prices are falling just as quickly. This proposed change attempts to increase the lighting efficiency in homes by encouraging higher efficiency Light Emitting Diode (LED) lamps while still permitting many CFL technologies. LEDs have been steadily gaining popularity over the last few years due to their higher efficiencies, better light quality (relative to Compact Fluorescent Lamps), and remarkably long lifetimes compared to traditional CFLs or incandescent lamps.
Proposal as PDF
HIGH-EFFICACY LAMPS Lamps with a minimum efficacy of 75 lumens per watt.
Analysis as PDF

This DOE proposal is progress, but lacks recognition that efficacy is not simply lumens per watt. It also pushes the envelope on achievable directional-LED efficacy at a number of 75, where in 2015, I am not aware of any compliant luminaire on-offer in our stores. I admit that 50 lumens per watt might be just fine until one is trying to pull needed light from a limited-capacity on-home photovoltaic array.

Here is one resource describing an alternative measure of efficacy, a Brightness Number.
Looking For A Reading Light (a printable pdf)
A Brightness Number rates delivered task illumination independent of light form. It assesses this number in side-by-side comparisons of a candidate with a known reference. The judgement is by human eye and by digital camera calibrated to record scenes in keeping with human vision. A 100 watt incandescent bulb is assigned Brightness Number B4. A directional light perhaps called "wide flood," of beam angle greater than 90°, say 120°, is a practical offering, B4 at 450 lumens. If the color temperature of the 100 watt incandescent reference is 3000°K, as I observe, choose a 3000°K LED as human-preferred, at reference B4. A world-accepted measure comparable to this Brightness Number might be at other color temperature, where some people like yellowing "warmth" of 2700°K better. Perhaps the standard and the wish for our home lighting, should be with broader spectrum, where in an LED with a large number of diodes, blue-LED coloring phosphors are a mix of yellow colors. Color-tunable OLED ,  with variable relationship to now-ancient light forms, will demand some flexibility in a Brightness definition.

The goal in our advance of efficiency in residential lighting shall be that a number of lumens delivered upon a task, shall be achieved at ever-less consumed power and overall measure of operating cost and environmental harm. Point-source lights will never measure up to this goal, and must now fall away from our high-efficacy future. A point source light will always be half as efficient as that beaming from a plate. It is simple physics understandable by anyone. LED and OLED elements are inherently least cost where flat, and that is a blessing. Let us then deploy these elements fully-revealed, a least amount of light blocked by decorative or practical aperture and by obscuring lenses. Let us place them flexibly and artistically, with least holder cost and with ease and safety of change-out. (Handling as to paint a ceiling, or from whim of rearrangement, never failure.) Let them generally be downlights, aimed downward from the ceiling or a lower-elevation pendant. Where LEDs might work essentially forever, let safety include absence of fragile elements that can not tolerate expected dropping, through lens breakage or failure of electronics. Let electronics durability match that of served diodes.

Most-efficient luminaires will not include the needless added expense and generally-awful compromise of a home's shell integrity, of a holder can. The best opportunity is to deploy luminaires in new low-voltage DC circuits, 24 vdc the apparent standard. Advocacy in this is expressed in a Google + Community , and in a Pinterest page .

I have offered this, as one suggested better statement in 2018, submitted to IECC:
Specific new rules of Referenced Standards shall support transition toward distributed local electric power generation and shall promote most-efficient lighting and appliances. At 2016 revision, special attention is given to most-efficient LED downlighting. Mention of passing forms of light is not helpful. In the process of evolution, less-efficient light forms, including all point-source bulbs, will be tolerated and not regulated, only as less-used decor. Market forces including evolving absence of Energy Star recognition will give natural drive toward best luminaire efficiency. Delivery of better luminaires is very important, as inspiration for all other efficiency gains. Lighting used abundantly at little or no cost, is important to productivity and quality of life. We do not develop purpose and hope, in cold darkness.

In reasoning that supports this submitted text, I expressed my understanding of math, to address cost impact of encouraging light forms that do not include can lights. I wish to develop that math, here. Illustration will include real examples from my experimental work as a weatherization contractor. My work is carefully documented and reported, to ensure a process of constant learning of better practices.

First, consider work done in a Southwest Portland Oregon attic, February- March 2014. The home, as usual, is notable as one where other contractors, following the guidance of regional policymakers Bonneville Power Administration , and Energy Trust of Oregon , would have found no work to be offered. The job was first an example in challenge of policies. I have needed to do more with my records, in challenge of existing policies and practices in lighting installation.

Prior posts for this Southwest Portland home are:
Daring To Collapse and Rebuild Crummy Loose-Fill Fiberglass Insulation 

Math Of Under-R12 Attic Floor Insulation Rule, For Incentives 

Photos for this post are in a captioned Picasa web album, Graphics for a can light replacement math study .

The Lighting Innovation:
It's routine. I do this wherever I fix attic insulation, by my own initiative.

I eliminated six Lightolier non-IC can lights. All had large annular gaps unobstructed at topside. If cans had been IC and covered, the insulation would have been fully blackened. The cans themselves were beautifully metal-spun and nearly airtight, high end for 1988 construction. What a waste. 

The can annulus diametral clearance was 7” - 6.25 = 0.75”, quite large. The frame was not pushed against the ceiling, and probably did not further constrict the passage of leaking air. Each can light had a gap of up to 7.8 sq in.  Apply Insulation Math for a Portland, Oregon home with a common 88%-efficiency furnaceThe annual cost of heating lost air is $0.555*Path Area, $4.30 per year. At four places I replaced a 65 watt incandescent downlight with a 750 lumens 14.5 watt LED. Another can that had a long-dead 65 watt incandescent was patched out. At the sixth can, over-sink, I installed a 450 lumens 9.5 watt LED in place of a 150 watt incandescent downlight. 

Apply Insulation Math . Completing insulation in the floor should save, at each light:
$2.4 * Baffled Area, sf* (1/3 - 1/50)  = $0.75 * Baffled Area, sf
= $1.30 per year for an 18” baffled circle (1.8 sf).
= $3 per year for 4 sf uninsulated over the kitchen sink.

There is about $6 per year typical savings from air sealing and insulating each very leaky non-IC can light. 

Here is a sampling of the job photos:

The found conditions are typical, an uneven bed of loose-fill fiberglass originally thought R19, trampled. Non-IC can lights are shrouded against insulation, by floppy R11 batt cylinders.

In thirty minutes, and for cost of about $25,  I replace the 7" can hole with a sealed-in drywall patch and RACO 175 junction box, texture matched.

This is the appearance of a can light patch, from the attic, now readily accessible by a wonderful drop-down fire-rated attic ladder.

The loose-fill always misses a band of at least 12" at attic eaves. Here there was no insulation under the batt shroud of a far-out non-IC can, over the kitchen sink.

Mud wasps will hate me.

Conserve electricity, in addition to $6 per year savings through air sealing and completion of insulation at each can light.

Vs. a 150 watt incandescent flood, a 4” Glimpse saves $368 + 1  = $369, over 32 years. Vs. a 65 watt incandescent downlight, a 6” Glimpse saves $380 - 136 = $244 over 32 years. Total savings operating four 6” Glimpse and one 4” Glimpse vs. six found lights, are: $369 + 5*244 = $1589. Divide by 32, for first-year savings: $50.  Call this $8 per light. Include the savings from sealing and completing insulation over the light, in the payback study. Those savings, with very-leaky non-IC can lights are about $6 per year. Total savings are $14 per year. It is right that the savings for a light eliminated are included, where new LEDs are much brighter. Five LEDs will give much more light than six old incandescents, and the LED lights might be dimmed most of the time. There might be even more savings, where old lights might have been brighter than needed, much of the time, and were not dimmable.

A savings of $14 in the first year is presented as typical of the opportunity in any can light replacement with a disk LED giving better illumination. The savings will persist indefinitely.This is an energy conservation savings subject to growth with rising cost of electricity. Perpetual energy savings are far more valuable than simple savings of money, as presented in post Perpetuity Math For Energy Conservation .

If the cost of electricity goes up with cost of scarce fossil fuels, a geometric rise of 10% per year , the future savings become far more important than those of an initial period where an investment is simply repaid. If you will use a new light where first-year savings are $14, Present value through twenty years is times-44, or $616. Present Value through thirty years is times-110, or $1548. Please seek a constructive understanding of such reality-based large numbers. First see that a payment of much more than $60 could be offered in exchange for the wealth now-yours, however large you perceive it. Be very happy if someone would do the work right, for $120. My work at $60 will be in short supply. Next, imagine that vs. doing nothing now, you might get your lighting forever after, at no cost, from your off-grid disaster-preparedness rooftop photovoltaic array and battery interface. You will want as much result from your investment as possible, not just some or all of your lighting, but maybe the charging of an electric vehicle off-grid! You will want lights of best-available efficiency, but know that fifty lumens per watt technology , durable and inexpensive since 2011, already gives nearly all of the achievable savings. Don't expect to save more than fifty cents per year for each luminaire, in a doubling of efficacy, from 50 lumens/ watt, to 100 lument/ watt. That's another $22 of present value through twenty years; not nothing, but little enough that one will only lose, waiting to act when better products arrive.

A basis presentation is done, I hope. Get back then to challenge of US Department Of Energy actions toward the 2018-2021 International Energy Conservation Code. The need in better building codes is about equally to save electricity, and to save thermal energy by eliminating awful bulb holders. It is about delivering needed task illumination, with ever-decreasing cost, within a power budget. How about this as High Efficacy definition? Where arrays of luminaires deliver a set amount of task illumination, the lifetime operating cost of high-efficacy luminaires is less than 10% that of 100 watt incandescent bulbs. A decent LED as A19 in a crummy can, will not measure up, since can energy losses must be counted. No point source light will measure up.

Look for that 90% savings vs. 100 watt incandescent, in this table. See that it is achieved now with very inexpensive LED disk lights, including GreenCreative 40834 with AC LED fitting even on a fully loaded ceiling box. No can lights, please. Where LED disk lights might serve for 100,000 hours or more, we already are well beyond 90% reduction, still with "efficacy" around 67 lumens per watt.

As a single parameter defining "high efficacy," Brightness/ Watts > 0.5 works. And maybe Brightness/watts = 1 is an achievable goal of inexpensive luminaires, 450 directional lumens from a 4 watt LED, 125 lumens per watt in useful directions. Brightness Number = Watts? Why not?

> 75 Lumens/watt does not promise efficiency, and seems a mean effort to continue sale of point-source CFLs, that often are ugly and not dimmable. Can CFLs get that efficiency? Why would we try?

No comments: