Low-E Coatings for HET Data & Conclusions 2 October 2002 John Good

Ambient 9ft. Ambient 86ft. Foil LO/MIT TiO2 Passing through Louvers?

Ambient 9ft. Foil LO/MIT TiO2 Ambient 86ft.

Ambient 9ft. Ambient 86ft. Foil LO/MIT TiO2 Passing through Louvers?

Ambient 9ft. Passing through Louvers? Ambient 86ft. Foil LO/MIT TiO2

LO/MIT Durability Tests Shoe Scuff Finger Nail Scratch

LO/MIT Durability Tests

LO/MIT Durability Tests

LO/MIT Durability Tests Shoe Scuff

LO/MIT Durability Tests

Conclusions ALUMINUM FOIL IS RECOMMENDED COATING: Performance - Foil Al Foil stays 2-5 times closer to ambient temperature in 3 out of 4 measurements. Installation – LO/MIT Both coatings are easily prepped and applied. Long Term - Foil Foil will probably stay cleaner than the soft & rougher surface of LO/MIT. Adhesion of foil is very good with no de-lamination problems reported by other Observatories. Assuming the foil ever becomes “heavily oxidized”, it will perform as well as a fresh, clean coating of LO/MIT. Maintenance - Foil Recoating of LO/MIT will be a given every 5-7 years. Multiple layers of gummy coatings. LO/MIT is a permanent decision. No other coating can be applied on top of LO/MIT. Removable only with solvents – power wash won’t do the trick. Al foil can be be re-laminated. Much easier if the adhesive lasts since removal of old layer would be difficult. No problems reported so far. Aesthetics – Foil Cost – LO/MIT (both costs are reasonable) Aluminum Tape: $35-37k $22k (tape & primer) + Labor (~6-8 man-weeks) + $7k (125ft. Man-lift) + $1.5k (Misc. Supplies). LO/MIT: $19-21k $5.5k (paint) + Labor (~6-8 man-weeks) + $7k (125ft. Man-lift) + $1,500 (Misc. Supplies).

DIMM Tower Foundation Poured last Friday. 15 tons of concrete. Good work McDonald Physical Plant!