Mon, 19 Oct 2026 06:51:52 +0100 https://www.greenbuildingforum.co.uk/newforum/ Lussumo Vanilla 1.0.3 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2417&Focus=237242#Comment_237242 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2417&Focus=237242#Comment_237242 Thu, 03 Mar 2016 20:15:31 +0000 rhamdu
Soon I expect it will be more economical, and better for the building's insulation, to install an off-grid PV panel on the roof, wired to energy-efficient lamps in the part of the building that lacks natural light.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2417&Focus=237245#Comment_237245 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2417&Focus=237245#Comment_237245 Thu, 03 Mar 2016 20:46:42 +0000 SteamyTea https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2417&Focus=237246#Comment_237246 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2417&Focus=237246#Comment_237246 Thu, 03 Mar 2016 21:15:58 +0000 Ed Davies
Assuming 2 hours lighting an evening and taking into account the need to source the energy for the extra heat-loss through the window (small triple glazed Velux) vs an approx 0.1 W/m²·K roof the capital cost of PV and batteries needed for lighting came out to £30 less, IIRC. The cost of the actual lights are not included as one would assume they're needed anyway.

For this application 2 hours an evening is probably an over-estimate. When it's sunny the PV energy can be used for other things but extra light through a north facing window isn't much use except when that corridor is in use.

I do regret not having a window to the north at all (other than in the light in the front door from the porch/greenhouse out) but maybe I'll spend that £30 on a webcam

Wookey has previously joked (I think it was a joke) about building a house with no windows at all - PV + LED lighting and web cams.

BTW, PV direct to LEDs (no batteries or anything) would work very proportionally as both are current devices. Just pick your LEDs so that each string has a total Vf just a bit less than the Vmpp of the panel. If you have multiple strings of LEDs then each would want a small resistor to keep the currents balanced.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2417&Focus=237250#Comment_237250 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2417&Focus=237250#Comment_237250 Thu, 03 Mar 2016 22:59:00 +0000 Gotanewlife https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2417&Focus=237257#Comment_237257 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2417&Focus=237257#Comment_237257 Fri, 04 Mar 2016 08:46:47 +0000 rhamdu Posted By: Gotanewlifethe light is not changed in any way and can only be blueish if the dome has been tinted. Good to hear a success story - albeit from a place where there is more sunlight and less concern about heat loss.
I don't know whether the light tube I saw was tinted. But since direct sunlight appears slightly yellow, and light from a clear or cloudy sky appears blue, I would have thought it was entirely possible for an untinted tube to emit a bluish light into the building. The subjective colours are affected by context: sky-light will appear more strongly blue if seen next to a 'warmer' light-source such as halogen lamps or the sun itself.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2417&Focus=237263#Comment_237263 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2417&Focus=237263#Comment_237263 Fri, 04 Mar 2016 09:43:12 +0000 Ed Davies
Absolutely - our eyes get very confused by adjacent colours.

http://www.slate.com/blogs/bad_astronomy/2009/06/24/the_blue_and_the_green.html]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2417&Focus=261652#Comment_261652 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2417&Focus=261652#Comment_261652 Wed, 27 Sep 2017 19:57:05 +0100 gravelld
I've an office on the N side of the house. Two narrow, shaded windows to the NW mean very little light, and I have to have the LEDs on whenever it's not bright outside. I also would greatly prefer daylight to LED light.

This is a lean-to, so a roof window is a possibility. However fitting that into the aesthetic is a bit difficult for a couple of reasons, and I think a sun pipe would look better from outside. With a short tube length I think this is ideal.

So now the sun pipe people appear to be getting their act together with numbers.

http://www.solatube.co.uk/products/ claim U down to 0.5W/m2K .

What about air tightness, anyone know?]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2417&Focus=261658#Comment_261658 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2417&Focus=261658#Comment_261658 Wed, 27 Sep 2017 20:35:28 +0100 djh
I'm also not encouraged by their mention of specific supposed aspects of Passive House, without being a certified component. Smoke and mirrors.

Their claim of 0.0345W/m2K for multi-foil also looks extremely dodgy.

The BBA and the 'Determination of LT, g-value and U-value of Solatube daylighting systems' documents contradict each other about the material the dome is made from, as well as the U-value, and don't cover the model you're discussing in any case.

Short of them producing a PHI certificate, keep the end of your barge pole clean.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2417&Focus=261660#Comment_261660 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2417&Focus=261660#Comment_261660 Wed, 27 Sep 2017 21:05:59 +0100 gravelld Posted By: djhI'm also not encouraged by their mention of specific supposed aspects of Passive House, without being a certified component. Smoke and mirrors.Yes, I thought that.

Will try to ring them.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2417&Focus=261670#Comment_261670 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2417&Focus=261670#Comment_261670 Wed, 27 Sep 2017 22:53:15 +0100 tony
Here they are a waste of time, insufficient light, too many downsides, plastic dome not durable enough.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2417&Focus=261672#Comment_261672 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2417&Focus=261672#Comment_261672 Thu, 28 Sep 2017 07:05:39 +0100 SteamyTea Posted By: tonyplastic dome not durable enoughI designed and manufactured some at the end of the last century. They are still in good condition.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2417&Focus=261673#Comment_261673 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2417&Focus=261673#Comment_261673 Thu, 28 Sep 2017 09:08:47 +0100 gravelld ]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2417&Focus=261710#Comment_261710 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2417&Focus=261710#Comment_261710 Fri, 29 Sep 2017 09:25:42 +0100 gravelld