Comments on: “lettuce” in – it’s cold out here! http://eatupag.com/2012/02/20/lettuce-in-its-cold-out-here/ the inside scoop on rooftop agriculture Mon, 17 Jun 2013 15:21:30 +0000 hourly 1 http://wordpress.com/ By: Tim Yon http://eatupag.com/2012/02/20/lettuce-in-its-cold-out-here/#comment-235 Thu, 22 Mar 2012 04:12:15 +0000 http://eatupag.wordpress.com/?p=748#comment-235 The key you are touching on is lengthening the growing season. Greenhouses naturally extend this season much as the same concept of espaliered trees on a castle wall. Yes, the challenge is to create a symbiotic relationship between the rooftop greenhouse with the building. It seems that in this climate where you have cold winters and warm humid summers, the spring and fall would be where you may be able to use the heated air to supplement the heating required by heat demand of the building. Natural convective currents within the greenhouse will draw cold air from the lowest wall openings and be drawn upwards toward the roof peak. Maybe incorporating evacuated tubes for hot water or some other thermal loops into the greenhouse structures would help. You would want to orient the long axix of your building on the east west axis.

]]> By: Lauren Mandel http://eatupag.com/2012/02/20/lettuce-in-its-cold-out-here/#comment-211 Tue, 21 Feb 2012 11:39:14 +0000 http://eatupag.wordpress.com/?p=748#comment-211 Thanks for your comment, Gregg! To tell you the truth, I’m not sure if insulation can be reduced with the use of a green roof – I’ll ask at work today. Recently, I’ve seen about 4″ of insulation required by code in PA when a green roof is in the picture (for new construction). I’m not sure how much is required without this vegetated topdressing.

You’re inclination about taller buildings is correct! In large municipal, institutional, and even multi-unit residential, the insulation lies within the roofing buildup. Sometimes it goes directly below the waterproofing membrane, and sometimes over top. Single-family homes are quite
different.

]]> By: Gregg Tracton http://eatupag.com/2012/02/20/lettuce-in-its-cold-out-here/#comment-210 Tue, 21 Feb 2012 03:24:16 +0000 http://eatupag.wordpress.com/?p=748#comment-210 I would guess that since the R factors are the composite of the roofing structure, a garden could be counted as part of the insulation even though you would occasionally vent it’s heat so as not to cook the plants too much. But in our house the attic air is typically very cold in the winter — the insulation is under the attic, not at the roofline. Perhaps in taller buildings which lack attic spaces this idea would work! Good thinking!

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