The ‘orange’ BRANZ book I keep talking about is now ‘red’.
For those of you using the BRANZ House Insulation Guide, you’ll be pleased to know they have brought out a new edition with nearly 50 percent more construction options and 28 new pages of information.
The new content includes:
- 10 options for steel-framed wall construction
- Deeper rafter options of 240 mm and 290 mm for a number of roof constructions
- 6 concrete slab constructions
- Work out the total construction R-value for a roof, wall or floor
- A redeveloped calculation table for recessed downlights
If you’re not familiar with the BRANZ House Insulation Guide it provides different wall, roof and floor constructions, and tables showing the R-value of insulation required to attain different construction R-values.
To find out more about the guide and how to purchase it click here.
By the way I don’t work for BRANZ – but I do find this resource very useful!
July 22, 2010 at 11:44 am
If the down lights change the total R value of the ceiling insulation and I see why they do, then why does it not change when you use Alf 3.2 to get a total BPI?
I went to a BRANZ seminar last year on how to use Alf 3.2 and the presenter assured me it did not come into the equation for that method of thermal modelling.
Matt Thompson
[Reply]
July 22, 2010 at 12:04 pm
Hi Matt,
Unfortunately ALF3.2 is one of the programmes I haven’t had a chance to get familiar with, so I don’t know how they have accounted for this.
[Reply]
July 26, 2010 at 9:07 pm
Dear Matt.
Every penetration you do through the insulation will make a difference to construction R value of the building. All that most do is add more insulation to compensate for the loss. Why anyone would use downlights is beyond belief. They have no benefit apart from a perceived idea that they are trendy.
Of concern to me is the fire hazard they create. I know that within the last couple of months a house that has a CCC, and was used for promotion by an organisation on National TV, has had to have all the downlights replaced throughout the residence (over 70 lights) due to the incorrect type being used. They had overheated and one caught fire. Fortunately the circuit breaker cut in and the fire extinguished itself.
Go into the ceiling space of any house that has downlights after they have been on for a couple of hours and it is very obvious where the heat is going once you put your head through the person hole (man hole to us that are not so PC).
[Reply]
August 6, 2010 at 3:26 pm
Hi bhavna
the question for today is consideration of using conpressed wall insulation with the higher R value in other areas, like the ceiling when space between the roof and ceiling is an issue? Also, the same as underfloor insulation between the first and second floors for both sound and thermal control?
cheers stew
[Reply]
bhavna prentice:
August 6th, 2010 at 3:52 pm
Hi Stewart,
If I understand your question correctly you are looking to use the wall product in the roof due to restricted space. The last paragraph of this post will explain that you can do this http://www.ebossnow.co.nz/bhavna-prentice/insulation-and-skillion-roofs.html.
Underfloor product may be used in midfloors, however it is not very thick so its acoustic properties may not be as good as Pink® Batts® Silencer® Midfloor.
[Reply]
August 10, 2010 at 10:14 am
Hi Bhavna,
Could you give me some information regarding the development of Hemp in insulation options? I know it’s a bit of a hot potato here in NZ but I think it’s high time that we get over the misplaced hemp phobia and embrace the enormous flexibility of the product. Talking to colleagues in the architecture field in Europe there is a growing interest in the combination with hemp and wool and a environmentally efficient insulation alternative.
I’m a strong advocate of a sustainable life style and try hard to maintain my vision in my design practice but it’s very difficult when the ‘powers that be’ try their best to curb any form of creative thinking.
Very keen to hear your point of view.
A preemptive thanks,
Harm
Studio ZEDD
Rotorua
[Reply]
August 10, 2010 at 2:15 pm
Hi Bhavna -
Do you know if an R value for plastered aerated concrete panels has been worked out (e.g. Integra, Hebel, ERFF, Celcrete)?
[Reply]
bhavna prentice:
August 10th, 2010 at 4:06 pm
Hi Bronwyn,
The R-value would be specific to each product, it is best to check with the product manufacturer.
[Reply]
August 10, 2010 at 2:54 pm
Does BRANZ take the space between floor joists into consideration for a multi story dwelling? is this not part of the thermal envelope?
[Reply]
bhavna prentice:
August 10th, 2010 at 4:15 pm
Hi Royce,
The thermal envelope of a multi storey dwelling is required to encapsulate the entire home excluding garages. The construction R-value of the exterior walls should take this into account.
[Reply]
david Curl:
February 24th, 2011 at 12:41 pm
The thermal envelope in a multi storey building would be the ground floor, external walls and ceiling/roof, just the same a single storey building. It is up to the client whether they insulate internal walls surround the garage or not, but the cionstruction of the garage door does make insulation difficult.
[Reply]
Royce:
June 30th, 2011 at 9:52 am
Perhaps I should re word my question. What is the best way to deal with the the space between the bottom of the top plate and the top of the bottom plate for the next story. The uninsulated ring in the walls thermal envelope? (between joists)
[Reply]
Bhavna Prentice:
June 30th, 2011 at 10:02 am
Hi Royce,
I see, this is a difficult one as once the cladding is installed insulation cannot be installed into this space.
For this reason I don’t believe this area is often insulated in practice. From the perspective of creating a good thermal envelope it should be insulated, but the insulation would have to be installed just before the building wrap and cladding went up. There is a similar issue with external corners, which i’m afraid we don’t have an easy solution to either.
August 10, 2010 at 11:33 pm
Are there any figures/measurements on the embodied energy of Batts insulation (or other insulation products), that can be compared against the energy savings they produce?
[Reply]
bhavna prentice:
August 11th, 2010 at 9:28 am
Hi Spencer,
We have done some work which shows the energy used during the manufacture of Pink® Batts® products, is offset by the energy saved by a home fully insulated with Pink® Batts® products within 3 (Dunedin)-15 (Auckland) months.
[Reply]
August 21, 2010 at 2:01 pm
Hi, in your experience are there any wall insulation materials that can rate at R2.8 for a 90mm cavity?
[Reply]
bhavna prentice:
August 23rd, 2010 at 9:49 am
Hi,
If you are referring to the Product R-value there is a 90mm Pink® Batts® Ultra® R2.8 Wall product readily available. However if you are wanting the actual construction to be R2.8 you would need a much higher R-value. PIR products are the most high performance product that I am aware, obviously this comes at an added cost also.
[Reply]
June 9, 2011 at 9:44 pm
John McGirr’s comments in regard to downlights is absolute nonsense !!!
there are downlights available which are C& A rated (ie Closed and Abutted) which prevents the insulation coming into contact with lamp itself.
The downlights which caused the problem where open type downlights and these were susceptible when used with Insul-fluff insulation and did in fact cause fires,
Incandescent downlights give a much better ambience than halogen lights for internal use. JB. Registered Electrician
[Reply]
David Curl:
July 2nd, 2011 at 10:11 pm
Hey JB.
Do you know the house John is talking about and it didn’t catch fire or do you know that the right lights were used and they still caught fire?
Just because you can lay Pink Batts right up to the recessed Closed and abutted lights does not in any way restrict the build up of heat in the ceiling space. bhavna will tell you that Pink Batts are virtually non ignitable, as are most batt products, so it is not the batts contacting the lights that is the problem. It is the heat build up when they are installed too close to an element which will ignite that is. Most times timber.
At the end of the day, every down light is a penetration in the thermal envelope and will impact on the efficiency of a building. A poorly laid batt that is creased can cut the efficiency of that batt down by 50%. A 50mm hole in the ceiling insulation every 5 square metres will downgrade the efficiency accordingly.
So what John posted is not absolute nonsense. Saying fibreglass insulation ignites if it contacts a lamp is. As is cutting holes in your insulation.
[Reply]
October 4, 2011 at 1:54 pm
We are replacing all the glasswool insulation as part of a residential renovation in auckland. Is there a sustainable method of disposal for old glasswool product?
[Reply]
Bhavna Prentice:
October 4th, 2011 at 2:14 pm
Hi Roger,
We currently don’t have the tecnology to recylce old glass wool insulation, particulary product that contains dust etc. In large commercial renovations the product in good condition is often given away. However if you have space you can add it as an additional layer in the ceiling and benefit from some additional thermal performance.
[Reply]
Roger:
October 5th, 2011 at 2:27 pm
Thanks Bhavna, unfortunately the client wants the old insulation removed due to dust/dirt etc, so will get the contractors to action the disposal.
[Reply]