I have previously carried out a worked example of the insulation of a Brick Veneer Wall, so as a comparison here is double brick wall.
I have also shown (in brackets) the effect of using a hebel block in place of one of the brick ‘leaves’:
|Outside surface air layer
|110mm brick (*or Hebel Block)
|Inside surface air layer
|Total R value
|U value = 1/R
The heat losses or gains for 150 sq m (fairly typical external wall area) of this type of double brick wall at 15 degrees above, or below, outside temperature will be:
Area x ‘U’ x temperature difference = watts per hour
150m2 x 0.51 x15degrees = 4410watts per hour
Heating/Cooling Requirement = 4.41kw/hour
Using Hebel for one of the leaves will improve the heat loss as follows:
150m2 x 0.81 x15degrees = 1822watts per hour
Heating/Cooling Requirement = 1.82kw/hour
Still not as good as the 1.17 kw/hour of the typical brick veneer construction
Don’t forget heat is also lost through windows, ceilings floors and ventilation.
See Insulation for similar Posts
For Posts about Green Building see Sustainability
A lot of people people misunderstand how Australian Standards apply to Contracts so here is a quick guide.
All Australian Standards (AS) are published by Standards Australia. which is a non-government organisation.
It’s role is to meet Australia’s need for relevant standards for quality in goods and services that are also consistent with international standards.
Each standard is a document specifying how a product, service or system can be practically obtained safely, reliably and consistently.
Role of Standards in Law
Australian Standards are not ‘Legal Documents’ and there is no automatic requirement to carry out any work or service to an Australian Standard unless:
- A Government Law, or Regulation, (Such as the Building Code of Australia BCA) requires that an Australian Standard applies; or
- The Specification for the project states that an Australian Standard will apply.
Even where an Australian Standard is mentioned you will quite frequently see words like: “or alternative that is deemed to satisfy the intent.”
Just because you are building in Australia don’t assume that Australian Standards will protect you as they may not even apply to the contracted work.
To understand the role of the Specification see: Contract Documents
Here is a new town house development in Melbourne.
Just a couple of ‘small’ problems
- Those huge master bedroom windows face west so they are going to get the summer sun all day from around 2.00pm until late in the evening.
- What makes it worst is it has full length mirrored wardrobes on the North Facing Wall
With the glare you will need to be wearing sunglasses just to go into the room. On a hot day it’s going to be around 60 degrees plus!
For more Fails and unusual houses go to What the………….?
When considering Overlooking you need to avoid having a ‘Direct Line of Sight’ into:
- A Habitable Room window. (The following link explains what a habitable room is: Habitable Room )
- A Secluded Private Space - Area primarily intended for outdoor recreation activities screened for at least 90% of its perimeter by a wall, fence or other barrier that is at least 1·5m high.
Windows are not considered to be overlooked if:
- One of the rooms in considered ‘Non- Habitable’ ; or
- There is a minimum offset of 1·5m from the edge of one window to the edge of the other; or
- The sill height of the ‘Overlooking’ window is at least 1·7m above floor level.
Obscured Window View
Another solution is to obscure the “Direct line of Sight’ by:
- Installing frosted glass or other obscured glazing in any part of the window below 1·7m above floor level. (Any window opening, when open, should not provide a direct line of sight) ; or
- Obscure with a permanent, fixed screen that has no more than 25% of its area open. An example of this type of screen is pictured below.
Screening Raised Open Spaces
A raised open space is considered to not Overlook a ‘Habitable Room’, or ‘Secluded Open Space’, if the ‘Direct Line of Sight is obscured by a permanent and fixed screen which has no more than 25% of its area open.
Non – Complying Designs
It may be possible to obtain consent for a non-complying design following a report to the council, although this will be difficult and is unlikely to endear you to your neighbour . . . . . Not Recommended!
An important issue when building a new house is Overlooking . . . . . . you won’t want to be overlooked by your neighbours . . . . . . and you need to avoid overlooking them!
The Regulations refer to a ‘Direct Line of Sight’ which has a particular meaning . This is based on:
- The view below a horizontal line 1.7m (a typical eye line) above the floor
- A horizontal view of 45 degrees either side of straight in front of the view.
- A horizontal distance of 9m
This is further is illustrated below:
View from a Habitable Room
The regulations are concerned with the view from a ’Habitable Room’ such as a living room, but not a ‘Non Habitable Room’ like a corridor. (see the following link to find out which are Habitable, and Non-Habitable rooms: Habitable Room )
Vertical Line of Site
Horizontal Line of Sight
View from a Raised Open Area
A Raised Open Space is an area of more than 2m2 above normal ground level and can include: Balconies, Patios, Decks, Terraces, or a landing.
Vertical Line of Site
Horizontal Line of Sight
There is no ‘Direct Line of Sight’ if . . . . . The floor level of the room or the raised open space is less than 800mm above ground level at the boundary, and there is a visual barrier at least 1·8m high at the boundary.
Someone sent me this picture entitled plumber fail of the year but that’s a bit harsh!
The plumber only put the toilet where the plan showed it! . . . and he didn’t design the floor plan.
Even then the situation could have been saved by the carpenter simply making the door open outwards rather than into the toilet! . . . . . . . . .Not only would this give more room in the toilet but it would be safer. (see why at: Separate Toilets)
For other posts about House layouts see Plans
More plumbing information and 24 pages of Check Lists in the ‘Selection / Pre-Start Guide’
What is a Habitable Room?
You see the phase in several planning and building documents with regard to things like Ceiling Height (see Room Height) and Overlooking.
Well according to the Building Code of Australia (BCA)
A Habitable Room is ” A room used for normal domestic activities”
Habitable Rooms Include:
- Living / Lounge / Family rooms
- Television Room/Home Theater
- Dining Room
- Sewing Room/Study
- Music Room
- Playroom/Family Room
Habitable Room Normally Excludes:
- Bathrooms / Ensuites / Toilets
- Laundry/Clothes Drying Room
- Walk-in Wardrobe
- and “Other spaces of a specialised nature occupied neither frequently nor for extended periods.”
Don’t like the builder’s standard Evaporative Cooling System?
A cost effective option I have found to work well is adding a centralised refrigerated unit to the standard ducted heating.
This means both systems share the same controls, fans, ducts and outlets. It will also operate for the same zones.
Some builders will allow this as an upgrade while others will want you to install the unit using your own supplier after handover.
If you can’t get the builder to include the cooling system you will nevertheless need them to do the following:
- Upgrade the duct sizes. Cooling systems need large diameter ducts than heating systems.
- Provide electrical power to the site of the external unit. (Contact your proposed cooling equipment supplier to find out the power supply that your system will need.)
This preparatory work should cost around $1,000 dollars for a single storey house.
A disadvantage of a central systems is it, like ducted heating, it is less effective in maintaining the required temperature in rooms that are closed off from the return air vent.