UKTC Archive

Re: Availability of sunshine

Subject: Re: Availability of sunshine
From: Julian Morris
Date: Aug 01 2019 12:14:07
PT Mapper produces the segments also, but like you I switch the layer off.

You've just done for me what I was planning to do this evening, i.e. work out 
what 5837 actually does and how far off reality it is. As you say, the 
segments are the motion of only part of a day of the year that doesn't exist. 
And no account of the density or shape of crown.  

It's made me realise something else though, I may contact you off forum about 
it.

Julian A. Morris - Professional Tree Services
jamtrees.co.uk  and  highhedgesscotland.com
0778 XXX XXXX - 0141 XXX XXXX


Sent: Thursday, August 01, 2019 at 12:48 PM
From: ""chris skellern" (skellernchris@xxxxxx.co.uk)" 
<uktc@xxxxxx.tree-care.info>
To: "UK Tree Care" <uktc@xxxxxx.tree-care.info>
Subject: Re: Availability of sunshine


 "As a separate question, how many consultants doing 5837 reports present 
the shadow segments in their tree constraints reports?"
 --------------------------------
I only include segments if requested. But by default, I plot them on to 
drawings because my software does it automatically. But I hide the layer so 
it can be switched on later if required.
The problem I have with the segment is that it (very roughly) represents 
the MOTION of the shadow through a short part of the day and can be very 
misleading. 
Firstly, its unlikely the area of the whole segment will be shaded at the 
same time. Using the height as its radius, it assumes a 45 degree sun 
elevation which is around 10am and 4pm in June, 10.30am and 3.45pm in 
May/July,  11.30 and 2.30 in April/Aug. Shadows in between will be shorter, 
outside will be longer.Using the segments northwest to due-east radius 
lines gives times of 11.20 - 5.50pm for June 21st. But in reality, at 
5.50pm the shadow length will be over twice the length of that shown! So 
the arc is a very, very rough guide to show where shading will occur during 
the summer months and during the middle of the day. 
You could have trees located very close to an eastern garden boundary with 
the segments making all kind of alarm calls. But in reality once past noon, 
the shadows have left the garden and are pointing westwards for the rest of 
the day. With tall trees on a western boundary, the segments may suggest 
that much of the garden is free from shade but in reality the whole garden 
could be swamped from early afternoon until sunset.
It is indeed a minefield!

Chris Skellern 
Arboriculturist

www.axciscape.com/
www.chrisskellern.com 
www.bonezsoft.com  LinkedIn   

    On Thursday, 1 August 2019, 10:08:27 BST, Julian Morris 
<jamorris@xxxxx.com> wrote:  
 
 Does anyone have a copy of "Availability of sunshine" (CP75/75 - AP 155) 
by BRE (01-Jan-1975) that I could have a look at? It is referenced in 
BS5837:2012 (Clause 5.2.2) but was withdrawn by BRE and is not available to 
buy, even from BRE. I don't need to HAVE a copy, i would just like a flick 
through it to confirm it says what I think it says. Any help appreciated.

As a separate question, how many consultants doing 5837 reports present the 
shadow segments in their tree constraints reports? Personally I do not do 
it, I offer it as a service (or full BS8206 daylighting assesments), no-one 
has ever asked for it and no-one has ever protested that I haven't included 
it in my reports.

Julian A. Morris - Professional Tree Services
jamtrees.co.uk  and  highhedgesscotland.com
0778 XXX XXXX - 0141 XXX XXXX
    


-- 
The UK Tree Care mailing list
To unsubscribe send mailto:uktc-unsubscribe@xxxxxx.tree-care.info

The UKTC is supported by Bosky Trees arboricultural consultancy
http://www.boskytrees.co.uk/





-- 
The UK Tree Care mailing list
To unsubscribe send mailto:uktc-unsubscribe@xxxxxx.tree-care.info

The UKTC is supported by Bosky Trees arboricultural consultancy
http://www.boskytrees.co.uk/