Report for CSR Hebel. Impact of various wall and floor construction options on 5 star compliance for two houses. by Tony Isaacs Consulting Pty Ltd

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1 Tony Isaacs Consulting Pty Ltd Sustainable Buildings Specialist Report for CSR Hebel Impact of various wall and floor construction options on 5 star compliance for two houses by Tony Isaacs Consulting Pty Ltd August 20, 2006

2 Executive Summary Two houses were evaluated using the AccuRate House Energy Rating Software for a combination of wall and floor types: Floors: Slab on Ground, Timber suspended, PowerFloor Suspended Walls: Brick Veneer, Fibre Cement clad framed walls and PowerPanel as the external veneer to a framed wall. Each house was modified till it achieved 5 stars and the differences in modifications required to achieve were examined in each case. Use of both PowerPanel and PowerFloor showed small but significant advantages and help to reduce compliance costs for insulation and glazing. Use of PowerFloor in the single storey house provides performance midway between a timber floor and a slab. In a two storey house use of PowerFloor on ground and upper floors provides the same or better performance as a slab floor. PowerPanel walls provide additional thermal resistance to external walls of habitable spaces and the subfloor. Both effects improve energy efficiency. Using PowerPanel as the external veneer instead of brickwork is particularly advantageous in two storey houses. The relatively high wall surface area means that heat flows through walls in a two storey house are much higher. Because there is a limited space for insulation in walls the extra thermal resistance provided by PowerPanel is particularly useful. A PowerFloor/PowerPanel house allows significantly easier compliance with 5 stars. Compared to the single storey house with insulated Fibre Cement framed walls and suspended timber floor the house constructed with Hebel floor and walls used 34.9 m 2 less double glazing, and 86 m2 less floor insulation. This would save construction costs in the order of $3 _ to 4,000. The same comparison with the two storey house shows that using Hebel saves 40 m2 of double glazing and allows significantly lower wall and ceiling insulation levels to be used. This would save construction costs in the order of $2 _ to 3,000.

3 1 Introduction Hebel products have a higher thermal resistance or R value than conventional building products which perform the same function. This higher R value results in improved thermal performance and should make compliance with the new 5 star regulations for houses. This report examines the impact of PowerFloor and PowerPanel walls on 5 star compliance for two houses: a single storey house of around 200 m 2 and a two storey house of around 260 m 2. It compares the changes required to achieve 5 stars for three different wall and three different floor systems: Floor systems examined: Concrete Slab on Ground, Suspended timber floor over an enclosed sub floor space, Suspended Hebel 75 mm PowerFloor panels over an enclosed sub floor space and as the second floor in the two storey house. Wall systems examined: Framed walls clad externally with fibre cement sheet. Note that subfloor walls are assumed to be a single layer of FC sheet when used with a suspended floor, Brick Veneer Walls. Note that subfloor walls are assumed to be a single layer of brickwork sheet when used with a suspended floor, and 75 mm Hebel PowerPanel used as a cladding on framed construction. Note that subfloor walls are assumed to be a single layer of PowerPanel when used with a suspended floor. The higher thermal resistance of the PowerPanel subfloor walls will reduce heat losses from through the floor. When hebel walls and floors are used and additional case with all internal walls and floors using Hebel was run as well. Upper floors between bedrooms/bathrooms and living areas will show a small but significant benefit due to the higher R value of the Hebel product. In addition walls between bedrooms/bathrooms and living areas will show a similar benefit. Each wall system is simulated with each floor system and the modifications required to achieve 5 stars are examined for each combination in each house. An Outer Melbourne climate based on Moorabbin airport was selected. This will be typical of the climate applicable to all new housing development in the south and east and ratings vary little with the climate assumed for north and south Melbourne. Only the inner city climate will show any significant difference in rating due to its warmer temperatures. 5 star compliance was determined using the AccuRate software by CSIRO version This was the latest version at the time of writing this report.

2 House Plans examined Plan: Single Storey House View from street (north) Figure 1 Single Storey House The base cases for this house were simulated with

Glazing was assumed to be generic aluminium framed clear single glazing.

4 2 House Plans examined Plan: Single Storey House View from street (north) Figure 1 Single Storey House The base cases for this house were simulated with no wall insulation and R2.5 ceiling insulation. No weather stripping or other air leakage control measures were assumed. Glazing was assumed to be generic aluminium framed clear single glazing. Most manufacturers products will have significantly better performance than the generic. This house is based on a house used by the Australian Building Codes Board to demonstrate the cost impact of the 5 star regulations in the 5 star Regulatory Impact Statement.

Ground Floor Plan Upper Floor Plan View from street (north) Figure 2 Two storey house The base

No weather stripping or other air leakage control measures were assumed.

Most manufacturers products will have significantly better performance than the generic.

5 Ground Floor Plan Upper Floor Plan View from street (north) Figure 2 Two storey house The base cases for this house were simulated with no wall insulation and R2.5 ceiling insulation. No weather stripping or other air leakage control measures were assumed. Glazing was assumed to be generic aluminium framed clear single glazing. Most manufacturers products will have significantly better performance than the generic. This house is based on a house used by the Victorian Building Commission to demonstrate the cost impact of the 5 star regulations in the 5 star Regulatory Information Bulletin.

6 To simplify the task of calculating 5 star compliance a suite of measures was applied to all houses and 5 stars was then achieved by adding either double glazing or floor insulation. Standard measures included: R3.5 ceiling insulation R2.0 wall insulation Air leakage measures: weather strip windows and doors, use self closing exhaust fans Use windows with improved frame thermal performance. For the purposes of this project a Bradnam s aluminium awning window was used. This has a U value of 6.4 compared to generic glazing of 7.6 resulting in 16% lower heat losses. Brick Veneer walls create a cavity joining the subfloor and attic. This was assumed to be blocked. If these measures achieved a rating over 5 stars insulation and air leakage measures were wound back till 5 stars was just achieved. If these measures were not sufficient to obtain 5 stars double glazing with a U value of 3.7 was used, for example an aluminium window with double glazing using a 10 mm air space. Floor insulation was assumed to have an R value of 1.5.

3 Results for base cases In their base case conditions the AccuRate software showed that these houses achieved the performance as shown in the graphs below.

7 3 Results for base cases In their base case conditions the AccuRate software showed that these houses achieved the performance as shown in the graphs below. Single Storey house Two Storey house Figure 3 Base Case Performance of houses with various wall and floor constructions The additional R value of the PowerPanel walls means that they perform significantly better than Brick Veneer or Fibre Cement when uninsulated. Note that in the single storey house the performance of the slab floor still offers a significant advantage over a timber floor and that the PowerFloor option falls between the two. The lower external floor area of the two storey house significantly reduces the performance difference between timber and slab floor options. The benefit of the PowerFloor to the upper storey means that the PowerFloor option actually outperforms the slab on ground.

8 Floor Wall Total Energy Use Compared to PowerPanel* PowerFloor Brick Veneer PowerFloor FC Sheet PowerFloor PowerPanel PowerPanel PowerFloor (& internal) Compared to Power Floor* Ground Brick Veneer Ground FC Sheet Ground PowerPanel Timber Brick Veneer Timber FC Sheet Timber PowerPanel *+ve means Hebel Product uses less energy Table 1 Simulation Results for single storey house Floor Wall Total Energy Use Compared to PowerPanel PowerFloor Brick Veneer PowerFloor FC Sheet Compared to Power Floor PowerFloor PowerPanel PowerFloor PowerPanel (& upper) (& internal) Ground Brick Veneer Ground FC Sheet Ground PowerPanel Ground & Hebel Upper PowerPanel Timber Brick Veneer Timber FC Sheet Timber PowerPanel *+ve means Hebel Product uses less energy Table 2 Simulation Results for two storey house

9 4 Achieving 5 star compliance in the single storey house. The table below shows the modifications required to achieve 5 stars for the various wall and floor constructions: Imp. window frame Air Leakage reduction Block wall cavity Area of Double Glazing Area of R1.5 floor insulation Wall Ceil. Floor Type Wall Type Ins. Ins. PowerFloor Brick Veneer R2.0 R3.5 Yes Yes Yes 17 0 PowerFloor FC Sheet R2.0 R3.5 Yes Yes na PowerFloor PowerPanel R2.0 R3.5 Yes Yes na 9 0 Ground Brick Veneer R2.0 R3.5 Yes Yes na 0 0 Ground FC Sheet R2.0 R3.5 Yes Yes na Ground PowerPanel R2.0 R3.5 Yes Yes na 0 0 Timber Brick Veneer R2.0 R3.5 Yes Yes Yes Timber FC Sheet R2.0 R3.5 Yes Yes na Timber PowerPanel R2.0 R3.5 Yes Yes na Table 3 Modifications required to achieve 5 stars for single storey house 4.1 Floor type Table 1 shows that additional R value provided by PowerFloor allows significant cost savings compared to using a timber floor. On average this house using PowerFloor will require 12 m 2 less double glazing and no floor insulation compared to the timber floor option. While using a slab on ground floor still allows lower costs than suspended floors this is as little as the cost of 9 m 2 of double glazing when both PowerFloor and PowerPanel products are used. 4.2 Wall type PowerPanel cladding adds greater thermal resistance to the external walls of rooms and the subfloor and its construction means that no wall cavities joining the subfloor and attic are present. Blocking the cavity reduces heat losses from the subfloor as does the higher R value of the subfloor walls. Use of PowerPanel clad walls allows less double glazing to be used to achieve 5 stars when the house is constructed on a suspended floor. PowerPanel clad walls offer a small advantage when used with a slab floor however, this was too small to matter when compared to Brick Veneer walls. PowerPanel walls show a significant advantage over framed walls clad with Fibre Cement sheet. Around 20 m 2 less double glazing was needed on suspended floors and 8 m2 on a slab floor due to the advantage of PowerPanel over the Fibre Cement walls.

10 5 Achieving 5 star compliance in the two storey house. The table below shows the modifications required to achieve 5 stars for the various wall and floor constructions: Imp. window frame Air Leakage reduction Block wall cavity Area of Double Glazing Area of R1.5 floor insulation Wall Ceil. Floor Type Wall Type Ins. Ins. PowerFloor Brick Veneer R2.0 R2.5 Yes Yes Yes 0 0 PowerFloor FC Sheet R2.0 R3.5 Yes Yes na 0 0 PowerFloor PowerPanel R1.5 R2.0 Yes Yes na 0 0 Ground Brick Veneer R1.5 R3.5 Yes Yes na 0 0 Ground FC Sheet R2.0 R3.5 Yes Yes na Ground PowerPanel R1.5 R2.5 Yes Yes na 0 0 Timber Brick Veneer R2.0 R3.5 Yes Yes Yes Timber FC Sheet R2.0 R3.5 Yes Yes na 40 0 Timber PowerPanel R2.0 R3.5 Yes Yes na Table 4 Modifications required to achieve 5 stars for two storey house 5.1 Floor type Table 2 shows that additional R value provided by PowerFloor allows significant cost savings compared to using a timber floor. It also shows that achieving 5 stars for the combined PowerFloor and PowerPanel option requires less modification than if the house was built on a slab. This is in part due to the extra insulation provided by the PowerFloor upper floor and PowerPanel subfloor walls. In general no double glazing was required to achieve 5 stars when using PowerPanel floors and lower wall and ceiling insulation levels were also used than with other floor types. 5.2 Wall type PowerPanel cladding adds greater thermal resistance to the external walls of rooms and the subfloor and its construction means that no wall cavities joining the subfloor and attic are present. Blocking the cavity reduces heat losses from the subfloor as does the higher R value of the subfloor walls. Use of PowerPanel clad walls allows less double glazing to be used to achieve 5 stars when the house is constructed on a suspended floor. PowerPanel clad walls offer a small advantage when used with a slab floor as shown by the lower wall and ceiling insulation levels.

11 6 Conclusion Hebel PowerFloor performs significantly better than a timber floor. In the single storey house using PowerFloor provides a performance level half way between a slab and a timber floor on average. In the two storey house with PowerPanel ground and upper floors the performance is around the same as the house with a slab. Hebel PowerPanel provides additional insulation to the wall. In two storey houses with a larger wall surface area than a single storey house this additional R value can be very valuable as the amount of insulation that can be used is limited to around R2.5 due to the width of the stud space. This additional R value helps to reduce the amount of change required in other areas when trying to achieve 5 star compliance. In addition, when used with a suspended floor the PowerPanel provides additional thermal resistance to the subfloor walls and reduces the extent of change required to achieve 5 stars. A PowerFloor/PowerPanel house allows significantly easier compliance with 5 stars. Compared to the single storey house with insulated Fibre Cement framed walls and suspended timber floor the house constructed with Hebel floor and walls used 34.9 m 2 less double glazing, and 86 m2 less floor insulation. This would save construction costs in the order of $3 _ to 4,000. The same comparison with the two storey house shows that using Hebel saves 40 m2 of double glazing and allows significantly lower wall and ceiling insulation levels to be used. This would save construction costs in the order of $2 _ to 3,000.

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