daylight harvesting system cost estimate

[stanlsimon]

I am looking for a ballpark estimate to install a daylight harvesting system in an elementary school. The light fixtures are newer model t-8's. would $3,500 per classroom cover the new ballasts, photosensor, controls, etc?

 

[davidbeach]

What does the electrical engineer on the project have to say about the costs and the paybacks?

 

[itsmoked]

daylight harvesting

What is that???

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[stanlsimon]

As part of an energy study of the building I am evaluating the economics of opening up windows that were bricked over during a 1980's energy conservation project.

Because the building was designed in 1917 the classrooms were designed with high ceilings and tall windows to allow good penetration of insolation to the back wall of the classroom.

Actually the lighting controls cost will be a small fraction of the window cost. Around 10%.

Does anyone have experience with electrochromic window surfaces? ie reliability, & documented variation of shading coefficient?

 

[itsmoked]

So you are talking about running inside lights 1 to 1 with solar power. No sunlight not lights?

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[stanlsimon]

The light flux through the windows would replace a percentage of the electrical lighting. Hence an avoidance of electrical cost. This would be joined by additional solar heating and offset by additional conduction losses and infiltration.

 

[Electic]

"Day light harvesting" seems like a lot of technology and new jargon to accomplish what the original windows did back in 1917.

I would investigate the proven life expectancy of "electrochromic" window surfaces prior to committing.

This kind of reminds me of when a undesirable open ditches became green project biofiltration swails.

 

[BJC]

" "Day light harvesting" seems like a lot of technology and new jargon to accomplish what the original windows did back in 1917."
Thats kind of what it is. If your next to the window you don't need the light on. The guy on the opposite side of the room may need the fixures over his desk on however. The energy codes in a number of states require that fixtures in a room next to the windows be switched and controlled seperately. If a room has on wall that is esentially glass the fixtures next to the windows would be controlled by an ambient light sensor. On a bright day the area next to the window will have enough light weather or not the fixture in that part of the room are on or off.
If it's a bright hot day and the blinds are drawn the control system would sense the blind position and turn the fixtures on at a lower lever. It usually takes more energy to run the AC system than to operate the fixtures next to windows.
Here's Californias energy code, only 108 pages for lighting. Reading it for a few weeks will make it very clear.

http://www.energy.ca.gov/2005publications/CEC-400-2005-006/chapters_4q/5_Indoor_Lighting.pdf

 

[itsmoked]

BJC;

I was just trying to get a grip on the term.. I did solar home judging for the state of California analysing 160 designs and we never came across that term...

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[BJC]

itsmoked.
I could have bbe using the term incorrectly. If so I wasn't the only one. The installations I worked on were commercial. If I google "daylight harvesting" now it seems a lot of manufacturers have ursurped the term and applied it to their control system.
to me and the ones I worked with it ment you should be able to turn off the lights by the window.
I am not doing any more lighting systems until they start making DALI ballest with unique identification switches. That way you can control ( a single twisted pair) and power to all the fixtures and control them anyway you can think of.
It seems to me the manufactures of existing lighting control systems are dragging their feet because a true DALI system would make a lot of control systems obselete PDQ.

 

[EEJaime]

Daylight harvesting is used when photosensors are used in conjunction with fluorescent switching or dimming to maintain a pre-selected lighting level. The new Lutron "Eco-lume" fluorescent dimming system is one such system. In California, our Title 24 energy code requires that any artificial lighting source in the daylit zone, (20 feet into the space from any fenestration and 2 feet to either side of window openings), be able to be reduced by 50% seperately from the remainder of the lighting. This would apply to skylights/dormers etc..., as well.

The costs really depend upon what system is selected. The aforementioned system for example, carries about a $125/ballast cost, plus some additional wiring and control devices. So in a typical 30 x 40 kindergarten class with 16-2' x 4' fluorescents, you can see that you are looking at 32 ballasts, (unless you tandem wire the fixtures). 32 x $125 = $4000.00+. That would be a tough payback period to sell. Unless you are going for some kind of LEEDS certification, the District would really need to be "Green-minded".

 

[stanlsimon]

Thanks, EEJaime for that helpful answer. I think the price will be coming down as the economy of scale kicks in. We have CIP (conservation improvement program) money from the Electric utility that will help the payback.

I used to do work in California back in the early 90's. At that time Title 24 did not really affect our design too much, mainly just a lot of paperwork.

 

[EEJaime]

As energy costs skyrocket, it has become much more stringent. We are involved in a major overhaul at Tom Bradley International Terminal at LAX and the electrical energy usage which accounts for about 41% of the terminal's annual energy consumption, translates into over 70% of the annual expenditure for energy. Our current design is 18% below Title 24 requirements and the City's energy consultants are still looking for added savings by the use of dimming, daylight harvesting and occupancy sensing devices.

 

[stanlsimon]

It seems like the manufacturers are slow to produce LED lighting, like they have too much invested in their T5's and T8's.

I have only seen a cople of commercial LED downlights.

 

[EEJaime]

The problem with LED technology for space lighting is that there are as many types of systems as there are manufacturers. No one has standardized the product as yet. Dimming is especially difficult. Color temperature is also a factor that needs further development. I think we are a good 5 years from having a good LED downlight design that can be equally and competitively manufactured by several of the major manufacturers. It should be a good solution, I just don't think we are there yet.

 

[Enermiser]

I have used Axis daylight harvesting ballasts. They include the photosensor and control directly in the ballast. You can get a 4lamp T-8 ballast for around $55.00 each. I poked the sensor through an adjacent ceiling tile next to the fixture. There were no other control wires and each fixture dimmed according to the light it sensed. I didn't have to worry about fixtures farther from the window because they compensated by them selves. i found them on the web

http://www.axistechnologyinc.com/

Good luck I found this to be a inexpensive alternative to other systems that had a lot of control wires etc.

 

[Hewlett]

BJC: Here is one ballast with DALI interface.

http://www.greentube.co.uk/page5.html