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Heated debate kicks off over Page/Park’s Carrochan

February 11 2010

Heated debate kicks off over Page/Park’s Carrochan
Loch Lomond & The Trossachs National Park Authority have refuted claims of poor insulation at their Page/Park designed HQ building made by local resident Angus MacMillan, who snapped melting snowfall on the roof of the premises.
MacMillan remarks of his contentious pic: “It shows the roof over the heated section of the Loch Lomond and the Trossachs National Park Headquarters had lost much of its snow almost immediately, obviously due to a significant heat loss from within the building, whereas the unheated area over the entrance was unaffected and remained snow covered until it thawed naturally.

“This seems to indicate the building is insufficiently insulated to retain its heat energy and, therefore, not achieving its claimed environmental sustainability.”
In response the park Authority affirmed of Carrochan: “It is important to point out that as expected the temperature of the roof over the heated area is higher than the temperature of the roof over the non-heated area. This will be the case regardless of the level of insulation as no insulation stops 100% heat loss. Therefore, it is not surprising that the snow melted more quickly over the heated area of the building.

“The canopy at the entrance is an outside space so the snow would take longer to melt, as it was being chilled from below as well as above.”


Angus Macmillan
#1 Posted by Angus Macmillan on 12 Feb 2010 at 09:04 AM
Nobody is saying that insulation stops 100% heat loss but other buildings in the area, including our own, did not lose their snow.

The pattern of melting on the roof shows a significant heat loss over a very short period.

And the snow in the foreground was not cooled from below.
#2 Posted by believin' on 12 Feb 2010 at 10:08 AM
The snow in the foreground may well have been cooled from below if the ground temperature was less than the air temp.
Angus Macmillan
#3 Posted by Angus Macmillan on 12 Feb 2010 at 10:19 AM
If i remember correctly there was a thaw before this snowfall.


"Soil temperature varies from month to month as a function of incident solar radiation, rainfall, seasonal swings in overlying air temperature, local vegetation cover, type of soil, and depth in the earth. Due to the much higher heat capacity of soil relative to air and the thermal insulation provided by vegetation and surface soil layers, seasonal changes in soil temperature deep in the ground are much less than and lag significantly behind seasonal changes in overlying air temperature. Thus in spring, the soil naturally warms more slowly and to a lesser extent than the air, and by summer, it has become cooler than the overlying air and is a natural sink for removing heat from a building. Likewise in autumn, the soil cools more slowly and to a lesser extent than the air, and by winter it is warmer than the overlying air and a natural source for adding heat to a building."
Angus Macmillan
#4 Posted by Angus Macmillan on 12 Feb 2010 at 10:24 AM
Sorry, I forgot to put the source of my quote above. Geo4va.
joe bloggs
#5 Posted by joe bloggs on 18 Feb 2010 at 16:53 PM
Insulation in most houses that do not occupy the roofspace will be at ceiling level....leaving a Cold Roof. In the Carrochan building the insulation is between the rafters as the roofspace is effectively utilised (as in an attic conversion). I think that this debate needs to stop there.
Angus Macmillan
#6 Posted by Angus Macmillan on 6 Mar 2010 at 22:57 PM
So there's a lot of wasted heat because of the height of the internals of the building which is not utilised and much of it is escaping through the roof. Why should the debate stop? I think you've given a good reason for it to continue.

joe bloggs
#7 Posted by joe bloggs on 7 Mar 2010 at 11:55 AM
Define wasted? Display an understanding of the overall environmental strategy for heating and ventilating the building - then there is a debate.
Does this 'wasted' volume contribute to those factors?
It seems to me at the moment there is little more to this than a hunch based on an old wifes tale about why snow melts on roofs and an aspiration for controversy.

Angus Macmillan
#8 Posted by Angus Macmillan on 7 Mar 2010 at 12:15 PM
"Define wasted?" Heating and ventilating an area which has a much greater volume than required for its purpose.

If one looks at the pattern of melting snow on the roof it is clear that a substantial amount of heat is escaping into the atmosphere in a very short space of time. Do you know if this has ever been evaluated?

joe bloggs
#9 Posted by joe bloggs on 7 Mar 2010 at 19:17 PM
Well then we are clear that there is no waste, the volume of the space is no greater than that required to serve its environmental and spatial needs.

it is that heat is escaping into the atmosphere based on what? As stated above there could be more than one reason for the melting snow.

Let me ask you a question - what are you to gain from your assault on this building? It has won many awards across disciplines of architecture, engineering and manufacture/contracting, and is a beautiful addition to the banks of the loch. Thoroughly appropriate in terms of local vernacular and current environmental thinking. Don't you agree?

Angus Macmillan
#10 Posted by Angus Macmillan on 8 Mar 2010 at 14:01 PM
"We" are not clear that there's no waste or that the volume of space is no greater than required, so please don't try to twist what I'm saying.

Taking into consideration the melting pattern a few hours after the snowfall, what explanation other than a significant heat loss do you have?

In answer to your question. I have nothing to gain personally. However, this building cost in the region of £9m of taxpayers money to construct, so as a member of the public am I not entitled to ask if it's environmentally benificial claims and awards are justified?

If not; why not?
#11 Posted by Amused on 8 Mar 2010 at 14:57 PM
He has a point Joe. The 'warm' roof construction argument doesn't wash I'm afriad. Even a 'warm' roof is supposed to keep the heat in!

stephen miles
#12 Posted by stephen miles on 9 Mar 2010 at 13:29 PM
It may be that both arguements are correct. The building may well be designed with a high spec warm roof system, which is deserved of its design awards and on paper meets high level of energy performance.
However, as now recognised in the soon to be released 2010 SBSA regs... Air tightness has been a problem within many new build schemes, as well as warm roof construction. It might be a combination of these which has resulted in the loss of heat through the roof. So whos to blame? Contractor? Sub-Contractor? Architect? Insulation Supplier? maybe all... maybe none.
Angus Macmillan
#13 Posted by Angus Macmillan on 9 Mar 2010 at 18:40 PM
I’m not sure how both can be correct. Surely desktop appraisals such as the BREEAM award at the “design stage” are hardly worth the paper they’re printed on if the completed project fails to meet the criterion on which such awards are based. I wrote to BREEAM asking them if they would like to comment but they didn’t reply. Does that say it all?

Likewise, in my view, if the Carbon Trust just looks up specifications and relies on the word of others about a buildings’ environmental sustainability, without carrying out its own detailed physical appraisal after completion, it makes a complete mockery of its award.

Does anyone know if this building was actually tested for heat loss after its completion?

However, the melting snow is only one aspect of my criticism of Carrochan’s environmental claims. Surely the building’s heated internal volume in relation to its usable floor space is well above that of a well insulated conventional building – and don’t start me on the building materials which came from as far away as Finland.

Surely all these factors should be taken into consideration before environmental awards are granted.

Do you not agree?
stephen miles
#14 Posted by stephen miles on 10 Mar 2010 at 13:17 PM
I am saying that the design may be correct, but the installation may not be. BREEAM 2006 and before does not have a criteria for checking buildings, although I think that some of the newer formats do. This still wouldnt cover things like build quality and air tightness.... hence the new regs. So to re-iterate, it may well be properly designed, and worthy of its awards, but badly contructed... I dont think that the rood sub-contractor won any awards to take away from him. :-) You are maybe being slightly aggressive when blaming the designers etc etc. Could be many explanations.
As for the cladding coming from Finland, no its not ideal, and for the space yes you could have deisgned a completely horrible little box space, but then at that point these is no longer any contribution in terms of material quality, thought, spacial quality.... essentially driving all and any architecture out... if you have issues with this one well designed building, why are you not on a raging tirade about the hoards of extremely poor developer and housebuillder junk which is lettering our towns and landscapes rather than being fairly negative about a well considered project. Just a thought.
Angus Macmillan
#15 Posted by Angus Macmillan on 10 Mar 2010 at 16:20 PM
I think you might be misunderstanding where I am coming from.

I’m not absolutely sure what you mean by a “correct” design, as any design will be subjective. Obviously the design of the Carrochan building pleased the client and that’s what the client got. Others may like or dislike the design but that is irrelevant.

I am not particularly directing my criticism at any trade or profession involved in the construction. However, if it was designed to be a low carbon building then, in my view, it has clearly failed in its purpose and someone should take the blame.

My criticism is primarily against the environmentally beneficial and sustainability claims made of the building that appear to be false in the light of heat emissions through the roof, the internal volume requiring to be heated in relation to useable floor space, and last but not least, much of the building material brought from afar.

If BREEAM and the Carbon Trust are basing low carbon awards on aesthetical design, spacial quality etc., then they are clearly not doing their job properly. Low carbon awards should be based on the energy efficiency of a building and I would venture to suggest that a well-insulated “horrible little box space” might well be the most efficient design.

Perhaps BREEAM and the Carbon Trust should have another look at this building but would they have the guts to withdraw their awards and admit mistakes? If they did, it might give the environmentalists some much needed credibility in the light of recent scandalous disclosures from the EAU and IPCC.
John Citizen
#16 Posted by John Citizen on 10 Mar 2010 at 23:23 PM
One of the Park's trumpeted aims is to encourage use of redundant buildings. There's rather a fine example less than a mile to the south, renovated at public expense and now lying half empty because of competition from a shopping complex supported by the Park. It has more than enough space to accommodate the Park's machinations. The Park wants to encourage use of local materials and boasted that the building did just that, yet the slates, stone cladding and plywood sheeting all came from outwith Scotland. OK the green Douglas fir was grown in Scotland but .......
I think the hype got up Angus's nose as much as the heat escape from the roof.
joe bloggs
#17 Posted by joe bloggs on 12 Mar 2010 at 21:20 PM
Im out of this debate...its going nowhere. know the score! And for the was built for £5m construction cost, and under a D&B contract....believe it or not......quite an achievement overall id say.
joe bloggs
#18 Posted by joe bloggs on 12 Mar 2010 at 21:22 PM
ps ever consider Angus, that the volume may serve a purpose in the environmental strategy under a slightly different topic than ventilation?
Angus Macmillan
#19 Posted by Angus Macmillan on 12 Mar 2010 at 22:20 PM
From the NPA website:
?An overall budget of £8.9m was secured from the Scottish Government in 2005. The project was delivered on budget with the headline costs:
?main construction contract including external works £4.9m
?site acquisition £500k
?internal fit out, furnishings, AV and IT equipment £1.5m
?professional fees £800k
?VAT £1.2m
Angus Macmillan
#20 Posted by Angus Macmillan on 12 Mar 2010 at 22:29 PM
#18 Although you say you're "out of this debate", would you care to elaborate on your thinking behind greater volume requiring less ventilation?

Are you considering that rising heat within the greater volume will require more energy to maintain a given temperature at ground level and lose most of the heat at the automatically ventilated windows at upper roof height?
joe bloggs
#21 Posted by joe bloggs on 12 Mar 2010 at 23:20 PM
interesting to see that the additional costs over and above construction cost were almost £4m, i did not know that.

I believe the volume aids in the stack effect natural ventilation achieved through the central 'street'

so its not that there is less ventilation, its that this contributes to achieving the required air changes without mechanical plant.
joe bloggs
#22 Posted by joe bloggs on 12 Mar 2010 at 23:31 PM
# i'm such a sucker and really should find something better to do with my time on a Friday evening#

buuuut whilst im here.....:-)

@post #11

if you take a temperature in a cold roof construction immediately above the insulation and another at roof level, immediately before the external face, there will be a difference.

everyone seemed to agree that no insulation is 100% effective. it just so happens that in a cold roof construction the outer face can often be well above internal ceiling level. meaning there is LESS heat to melt the in your typical developer semi.

carrochan is a warm roof, and this level of void does not exist.

do the panel think this may be an explanation?
Angus Macmillan
#23 Posted by Angus Macmillan on 13 Mar 2010 at 09:06 AM

Joe, I’m not sure I follow your logic here.

It is my understanding that what you are describing as a “cold roof” is one where insulation is placed above ceiling level and the void area of the attic space will have very little heat from the occupied building below. Nevertheless, there will always be a heat difference from the lower to the upper part of the void even if no heat is coming from below, because any heat or cold intrusion from outside weather influences cannot be ignored as the roof itself does not have any insulation.

However, with the “warm roof” the insulation should be just as effective in preventing the passage of heat to the outside atmosphere as the “cold roof” has of passing it to an attic void.

It seems clear to me that the Carrochan building’s insulation is insufficient to prevent much of the heat escaping into the atmosphere and therefore not living up to its environmentally beneficial claims – and that is why I’m questioning the validity of its awards.

I’m not sure who the “panel” is here but I think if there is one, perhaps they should join in the debate.
#24 Posted by wang on 13 Mar 2010 at 14:32 PM
Angus, the traditional cold roof build up also incorporates continuous ventilation into the roof space, therefore the temperature in the void will be close to the outside air temperature, meaning the surface temperature of the finish has hardly any relation to the internal temperature of the building.
In a warm roof the ventilation space is usually right under the roof finish, this is needed to allow moisture to escape and prevent condensation build up within the insulation layer.
Insulation and waterproof membranes are designed to breathe to allow moisture out, which in turn means a certain amount of (warm) air will also escape.
The short distance between insulation and finish makes the roof finish surface temperature higher on the warm roof construction, which would melt the snow...
it would be useful if anyone form page/park reading these comments could post a construction detail :)
Joe bloggs
#25 Posted by Joe bloggs on 13 Mar 2010 at 19:17 PM
Wang hits the nail on the head. It would seem to me that this is the likely explanation and without further info on what exactly happened to the surrounding buildings at the same time and the construction of those buildings. There really is no debate to be had.


Angus Macmillan
#26 Posted by Angus Macmillan on 13 Mar 2010 at 20:44 PM
Wang, I agree with your first paragraph, although there might be a small change in temperature because of any heat rising to the apex of the roof.

However, a clear vertical height of 40ft from ground floor to the apex of the warm roof will require additional heat energy to maintain a given temperature at ground level. This wasted heat energy means the upper area will be considerably hotter and a substantial amount of that heat is escaping through the roof as can be seen by the almost immediate melting of snow.

You’re right, it would be interesting to hear from page/park and see what they have to say.

I have forwarded the url of this discussion to BREEAM and The Carbon Trust to give them the opportunity to comment :-)
Angus Macmillan
#27 Posted by Angus Macmillan on 15 Mar 2010 at 10:14 AM
#16 John Citizen
Yes John. It seems just about everything the NPA is built on is "hype" the one exception being the foundations of Carrochan itself which was a fairly solid car park that was snatched from public use.
But it's interesting you should mention Douglas Fir as I understand it is an "alien species". You'd think the NPA would have wanted nothing to do with it out of principle.

Angus Macmillan
#28 Posted by Angus Macmillan on 15 Mar 2010 at 10:19 AM
#25 Joe, you seem terribly interested in this debate being stopped. Why is that? Can I put a similar question to you that you put to me earlier?

What have you to gain from stopping the debate on this building?

Robert Crighton
#29 Posted by Robert Crighton on 16 Mar 2010 at 11:14 AM
Angus, most interesting. You seem to be throwing the gauntlet down to Breeam and the Carbon Trust and if you really have informed them of this debate it surprises me they haven't commented. I think Page/Park should also comment so I am sending them a link to this debate and as Yang suggests post a construction detail.

Angus Macmillan
#30 Posted by Angus Macmillan on 16 Mar 2010 at 14:48 PM
#29 Spot on Robert. I have emailed BREEAM and the Carbon Trust on two occasions about this and in the latter advised them of this discussion and provided them with a link. They should be able to defend their awards or withdraw them.

I don't think it matters whether the roof is "cold" or "warm". The bottom line should be that Carrochan shouldn't be spewing heat energy into the atmosphere if it's a "low carbon" building no matter how aesthetically pleasing the design. It'll be interesting to see what page/park have to say if they respond to your approach.

#31 Posted by wang on 16 Mar 2010 at 16:42 PM
angus, my point was; no matter the roof construction, the heat loss will be the same between the inside and outside, but on the warm roof construction it is much easier to see when there's snow on the roof.
The idea that this is "spewing" more heat engery than other buildings is very likely not the case - but since i have no inside knowledge of the construction detail it's impossible to confirm... although things like this is why we have minimum requirements in the building regulations :)
Angus Macmillan
#32 Posted by Angus Macmillan on 17 Mar 2010 at 08:33 AM
#31 Wang, as "amused" said above, "The 'warm' roof construction argument doesn't wash I'm afriad. Even a 'warm' roof is supposed to keep the heat in!"

The building is clearly not heat energy efficient for the reasons I have given above. There's no point in heating internal volume that is excess to requirements and spewing it through the roof to melt snow almost immediately after it has fallen.

#33 Posted by wang on 17 Mar 2010 at 08:48 AM
whilst you think that reason might not wash, that is the reason the snow is melting on the roof! As discussed before, the same amount, maybe even less energy is escaping from warm and cold roofs, it just manifests itself in different ways.
Angus Macmillan
#34 Posted by Angus Macmillan on 17 Mar 2010 at 10:33 AM
#33 Wang, I'm interested to know what evidence you have for these claims. Can you post a reference to back up what you say?

#35 Posted by amused on 17 Mar 2010 at 12:25 PM also commended in the civic trust awards.
#36 Posted by wang on 17 Mar 2010 at 12:29 PM
Evidence for my claim that the heat loss through both construction methods is similar can be found in the building regulations! these have a maximum value for heat loss for elements of the building, if the construction method allowed for greater heat loss than the regulations require, a building warrant would not have been issued and the building not constructed. If both construction methods are designed to meet the maximum heat loss requirements they both lose the same amount of energy.
current regs require 0.25W/m2K for non domestic roof and 0.20W/m2K for domestic roof - so whilst an office building may have a lesser requirement than domestic, the actual construction method, cold/warm/flat, must still meet these standards.
It seems you have a bee in your bonnet about this particular building, maybe your next step should be to get some thermal imaging done of the building, rather than citing melting snow as an indication that the buildings entire energy strategy is a complete failure.
Angus Macmillan
#37 Posted by Angus Macmillan on 17 Mar 2010 at 14:33 PM
#36 Wang, the 0.25W/m2K evidence you've provided is for a maximum for all non- domestic roofs not for the difference between cold and warm roofs.

If, as you said earlier, a cold roof void “will be close to the outside air temperature” there must be little or no heat energy escaping above eaves level. There is also the point that a volume equivalent to the void in a cold roof is being heated unnecessarily as in the warm roof of the Carrochan building. People in an office don’t need a heated headroom of circa 6 metres, or in other areas circa 12 metres. So it seems to me that there is a considerable waste of heat energy even before it spews through the roof.

But that is presumably what the client wanted and what they got in aesthetically pleasing terms, and perhaps - like the Scottish Parliament – more of a monument to their existence as an authority.

However, what I’m questioning is why it has been awarded low carbon awards by BREEAM and the Carbon Trust when it seems obvious to me that a well insulated building with a headroom of perhaps 3 metres and further insulated at eaves level would probably consume much less energy. Don’t you agree?
#38 Posted by wang on 17 Mar 2010 at 16:05 PM
the point is, if both types of construction are built to the standard required by the building regulations they will lose the same amount of heat, therefore there is no difference between the construction methods!
As we have discussed before the reason the attic space in a cold roof has a temperature close to the outside air is because the space is vented directly to the outside air.
Also discussed previously is that the height of the space in this particular building may be being used to create a stack ventilation effect, it may seem to you that this is a considerable waste of heat, but if it is limiting the amount of mechanical ventilation required then this is the trade off. Overheating in an office space full of people and computers can be a much more difficult issue than the basic space heating requirements. Ventilation to remove excess heat and maintain a comfortable temperature for users can take a massive amount of energy and effective natural ventilation strategies can provide a great saving in the overall energy strategy in a building.
the breeam award takes into account the overall building strategy, not for a single element, you say the heat is wasted in the building but it could be serving another purpose... obviously a lesser volume would demand less energy to heat it, but a reduced height would also reduce any stack effect for air movement.
Would you have preferred that this building was designed with standard ceiling heights and a heavy reliance on air conditioning like many other office development, won no awards for anything and required more public money to keep it running?
Angus Macmillan
#39 Posted by Angus Macmillan on 17 Mar 2010 at 20:42 PM
#38: Wang, you are absolutely wrong to say “if both types of construction are built to the standard required by the building regulations they will lose the same amount of heat, therefore there is no difference between the construction methods!” To start with, the standard is the “maximum” heat loss allowed, and a “low carbon” building should be substantially below that level.

The idea that the attic space in a cold roof is solely because it is naturally vented to the outside air is also nonsense. There are many old buildings that are not vented to the outside that have temperatures very close to the outside because they have been well insulated at eaves level which prevents the passage of heat upwards.

Stack ventilation is as old as the hills and can be incorporated in virtually any design of building without the necessity for a large amount of wasted heat or mechanical ventilation. Indeed, I understand the roof lights at Carrochan open automatically in a similar fashion to a greenhouse so there’s probably no requirement for the roof to be leaking heat energy for ventilation purposes. And you’re jumping to extremes when suggesting the alternative would be air conditioning. Natural ventilation is much more desirable and healthier.

Take another look at the photograph and you’ll see that heat energy has shifted latterly - and probably mechanically assisted as well - to each end of the heated part of the building where there are upper floor offices and function rooms. You’ll see the snow has melted off these areas completely. And look at the pattern of melt in the middle; that’s not designed within the overall warm roof system. To me it’s pretty obviously leakage of heat energy through insufficient insulation.

Both the BREEAM and Carbon Trust awards were for low carbon buildings and it doesn’t surprise me that so far they haven’t commented. I wonder why?

#40 Posted by wang on 17 Mar 2010 at 22:30 PM
U-values are the calculation tool we use for energy transfer across an element of a building, are you saying that a cold roof designed to meet the 0.25W/m2K and a warm roof designed to meet the 0.25W/m2K lose a different amount of energy??
Continuos ventilation of roof spaces is extremely common, a requirement for domestic buildings, please see section 3.15.7 of the regulations to explain this "nonsense".
I have been in several offices with standard ceilings and air conditioning, i don't think it's an extreme view to say that this is a common alternative to stack ventilation at all...
again however, i would point out that the awards are for the OVERALL building strategy and not purely for the roof insulation, if this building had won an award from celotex or kingspan for the most air tight, energy effiicient roof construction then maybe you'd have a great case, but until the whole building strategy has been examined and understood i don't think your argument can hold any real weight about the awards won.
I have come to the end of my contributions on this thread as i see no reason to continue, I hope that you can get a copy of the energy strategy for this building at somepoint and put your mind to rest,


Angus Macmillan
#41 Posted by Angus Macmillan on 18 Mar 2010 at 09:23 AM
#40 Wang, I have already answered your question in the previous post. The standards are the maximum amount of heat loss allowed so a low carbon building should have a roof designed well below that. I don’t think you’ve seriously considered anything I’ve said in the previous post so we’ll just have to agree to disagree.

As far as I’m concerned, the bottom line is that a building with low carbon awards shouldn’t be spewing out heat energy through its roof that melts snow almost immediately after it has fallen. And it’s significant that those who probably have the answers haven’t responded here despite being made aware of this discussion.
#42 Posted by entertained on 19 Mar 2010 at 09:51 AM
yawn yawn, controversy...the reason has been presented to you over and over and over and over and over......

anyone like hot chip?!
Angus Macmillan
#43 Posted by Angus Macmillan on 19 Mar 2010 at 19:44 PM
#42 What I find really "entertaining" is that no-one involved in the design or awards has come with any reason and if you think they have perhaps you need to eat properly by keeping off chips and have some sleep to stop you yawning :-)
Ian Imlach
#44 Posted by Ian Imlach on 20 Mar 2010 at 01:05 AM
I see nothing in the photograph too suggest that
this building "is a beautiful addition to the banks
of the loch", irrespective of it's insulative qualities.
Angus Macmillan
#45 Posted by Angus Macmillan on 22 Mar 2010 at 22:21 PM
Freedom of Information Request to Loch Lomond and the Trossachs National Park Authority 22 March 2010.

1. Information to verify the claim on the Loch Lomond and the Trossachs National Park Authority’s website that “the expected carbon footprint of the building is 80 tonnes as compared to 200 for a conventional building and 140 tonnes for current best practice”, has been achieved in reality in respect of the Carrochan headquarters.

2. What percentage of generated heat energy is lost through the roof of the building?

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