What is the formula?

Discussion in 'Landscape Lighting' started by Mataman, Jul 16, 2008.

  1. Mataman

    Mataman LawnSite Member
    Posts: 83

    What is the formula to compare line voltage to low voltage electrical costs?:confused:
     
  2. Lite4

    Lite4 LawnSite Gold Member
    Posts: 3,112

    There really isn't a formula. A watt is a watt whether it is 12v or 120v. What you look at is lamp efficiency. For example lumen output. A 20 watt mr-16 in a 12v system will probably give you 4 times the lumen output of a standard incandescent line voltage bulb, depending on what you are comparing it to of course. You have to look at the photometrics and compare. The real savings though comes when you start comparing installation costs between the two.
     
  3. INTEGRA Bespoke Lighting

    INTEGRA Bespoke Lighting LawnSite Platinum Member
    Posts: 4,102

    A KWh consumed is a KWh consumed. It does not matter if you use 100w at 12V or if you use 100w at 120v.

    Take your load in watts,
    Divide by 1000,
    Take the remainder and multiply by the number of hours in operation,
    Take the result and multiply by the (real) cost of a KWh of electricity in your market.

    Example. 600w trans / 1000 = 0.6 X 6 hours per night = 3.6 KWh x $0.14 per KWh = $0.50 per night.

    Now, make sure you figure out the "real" KWh cost of electricity in your market. This would include all of the taxes, fees, delivery costs, debt retirement charges, etc etc that the power company adds to your bill. Here the "real" cost of our electricity is about $0.14 per KWh.
     
  4. steveparrott

    steveparrott Sponsor
    Posts: 1,190

    The figure most often quoted is that low voltage lighting consumes about 1/3 the energy of 120-volt lighting.

    This is a very rough estimate based on the several factors including:

    Luminous efficacy (lumens/watt) - 12V halogen is about 15 lm/w; 120V incandescent is about 10 lm/w - a 50% savings.

    More appropriate lamp wattage selection: outdoor floods are typically 75W or 150W or more; 12V lamp choices of 20W, 35W, 50W, etc. This means that appropiate brightness levels are easily achieved - a 35W tree light easily replaces a 150W flood (about 75% savings).

    Better control of light spread - more efficient use of lumens dependant on lighting design and fixture design.

    There's a lot of variation in the above factors so an attempt to nail an actual number is difficult.
     
  5. Mike M

    Mike M LawnSite Bronze Member
    from usa
    Posts: 1,941

    A quick reference sheet on figuring the cost to operate a particular system (assuming you know the approx. total wattage) is available from CAST, I have it on a photocopy, I think. You check their website resources.
     
  6. Mataman

    Mataman LawnSite Member
    Posts: 83

    ahhh, I'm screwed. There's an electrical company in town that is destroying the low voltage market. They're putting in bollards for $100 each,,, installed! I guess they're trying to keep payroll up since the housing market has crumbled.

    bids I've lost to them last month(their fees);
    - 18 bollards and 5 spots for under $3,000
    - 19 spots for $2500
    - 14 paths, 3 wall wash, 12 spots, guessing $4500 @ the most

    The home owners/HOAs are more worried about upfront costs. Of course when they see a $3,000 bid and then a $10,000 bid, they're figuring years and years to recoup the difference.

    I've tried to explain this to the customers over and over but it's like they don't believe me. Kinda like when concentrated liquids came out, nobody believed that you could get the same results with less liquid. Now in this case, less watts.

    Thanks for your quick responses.
     
  7. steveparrott

    steveparrott Sponsor
    Posts: 1,190

    Hearing that the electrical guys are beating you up on price, you'll need to take price out of the equation by strongly differentiating yourself as a lighting designer.

    I assume that you deliver better lighting design, that you are passionate about landscape lighting, that you are an artist, that you transform the homeowner's nighttime experience! That you use the highest quality and best performing products. The value of all that is recognized by your target high-end market.

    Your task is to effectively communicate how you are very different from the electrical guys. You need a great website, great presentation material, a good demo kit and learn to speak with great passion about your design ideas.

    Let the electrical guys take all the jobs from penny-pinching homeowners. You don't need that work, you need high-end homeowners who are willing and able to pay for value.
     
  8. Lite4

    Lite4 LawnSite Gold Member
    Posts: 3,112

    You are definitely fishing your gear a little too deep in the pond. If all you seam to be encountering are SUCKERS and other bottom feeders, you need to change your bait for the appropriate fish and raise it from off the bottom so you can present it where the trophy fish live. Trophy bass and trout always seem to share the water with suckers and mud dogs. You just need to be a skillful enough angler to know how to catch them. (Sorry for the fish analogy) EC's will only be able to put out product like that for so long. I can't imagine they are making much of any money unless they are cutting corners somewhere and even then, Yikes, Thats gotta be some POWERFUL ugly lighting. Keep on Fishin.
     
  9. JoeyD

    JoeyD LawnSite Silver Member
    Posts: 2,933

    I love that anology.....I might have to steal it!! LOL
     
  10. Mataman

    Mataman LawnSite Member
    Posts: 83

    HA! You guys kill me!:drinkup:

    Actually, these all have been in some very high dollar areas. The bollards gig is very snooty, only problem is that there is an engineer and GC that I know and are certified "Cheap". The lots alone start @ 650,000 but average 1 million for water front. Most of the houses on the water front sit on two lots.
    Get this, they told me yesterday that they plan on putting those
    "energy saving" bulbs in all the bollards to cut costs.
    What I need is to find an HOA that specifies in their bylaws that all homes must have lighting and the board members will all be clueless nurses.:cool2:
     

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