Wood and Energy EfficiencyLightweight Timber Framed Construction and NSW’s BASIX Thermal Comfort
Wood and Energy Efficiency – Lightweight Construction © FWPA 2011
Learn more about wood at UTAS
Centre for Sustainable Architecture with WoodGraduate Certificate in Timber (Processing & Building)• 4 units, part time, onlineAreas covered include:• Wood science• Design for durability and service for life• Timber as a renewable resource• Sustainable design and construction• Engineered wood products• International technologies and developments• Plus, selected topics of individual interestMore information: Associate Professor Greg Nolan (03) 6324 4478 or [email protected]
Wood and Energy Efficiency – Lightweight Construction © FWPA 2011
Learning Objectives
After this presentation you should be able to:– Understand the thermal comfort methods of
BASIX– Understand the thermal properties of wood– Understand how wood products can meet BASIXs
thermal comfort requirements
For architects - AACA Competencies:– Design– Documentation
Wood and Energy Efficiency – Lightweight Construction © FWPA 2011
This Presentation
• Thermal comfort requirements of BASIX• How wood-based construction systems can
meet these requirements• Simple techniques to insulate:
– walls, roofs– sub-floor
• Ventilation issues• Smart use of thermal mass
Wood and Energy Efficiency – Lightweight Construction © FWPA 2011
BASIX - Thermal Comfort Requirements
Methods:– Simulation (AccuRate, BERSPro, Firstrate5)
• Whole house must not exceed maximum (separate) heating and cooling loads
– Deemed-to-satisfy• DIY• Rapid – simple single storey detached dwellings
– All methods require some form of additional insulation
Wood and Energy Efficiency – Lightweight Construction © FWPA 2011
Thermal Properties of Wood
Timber / wood product Density (kg/m3)
Thermal conductivity
(W/m.K)
Thickness(mm)
R-value(K.m2/W)
Framing timber - kiln dried hardwood (across the grain)1
677 0.16 12 0.0819 0.1250 0.31
100 0.621 000 6.25
Framing timber - radiata pine (across the grain) 1
506 0.10 12 0.1219 0.1970 0.7090 0.90
1 000 10.00Particleboard flooring1 640 0.12 19 0.16
22 0.1825 0.21
1 000 8.33Plywood flooring1 530 0.14 6 0.04
12 0.0919 0.1425 0.18
1 000 7.14
1calculated based on values and method provided in BCA 2010 Volume One Specification J1.2 Table 2a.
Wood and Energy Efficiency – Lightweight Construction © FWPA 2011
R-values for Timber Framed Elements
Wood and Energy Efficiency – Lightweight Construction © FWPA 2011
Roof
Insulation is required in all climate zones in NSW
Wood and Energy Efficiency – Lightweight Construction © FWPA 2011
Walls
Insulation is required in all climate zones in NSW
Wood and Energy Efficiency – Lightweight Construction © FWPA 2011
Floors
• Increase in floor system R-value required in most climate zones in NSW
• Additional insulation required in Rapid Method
Wood and Energy Efficiency – Lightweight Construction © FWPA 2011
Floors: BASIX requirements
BASIX Requirements - (DIY Method)Typical Insulation Options for Suspended Floor Construction
(for floors without floor heating system)
Climate Zone 2 4 5 6 7 8 2 4 5 6 7 8Perimeter Treatment Enclosed Unenclosed
Minimum required Total
R-value0.7 1.7 1.3 1.7 2.0 2.5 0.7 2.0 1.5 2.0 2.5 3.0
Total R-Value of Framed and
Concrete Floor Systems
0.7
Minimum additional R-
value required (down)
Nil 1.0 0.6 1.0 1.3 1.8 Nil 1.3 0.8 1.3 1.8 2.3
Wood and Energy Efficiency – Lightweight Construction © FWPA 2011
Floors: Increase system’s R-value
• Additional insulation techniques:1. Insulate above the floor (e.g. carpet)2. Enclose sub-floor perimeter wall3. Decrease air-flow:
• Cover ground with plastic / halves ventilation• Install cavity barrier into external wall cavity
4. Insulate under floor:• Insulate sub-floor perimeter wall • Insulate directly under floor
Wood and Energy Efficiency – Lightweight Construction © FWPA 2011
Sub-floor: Enclose sub-floor perimeter
Wood and Energy Efficiency – Lightweight Construction © FWPA 2011
Floors: Enclose sub-floor perimeter
• Increase R-value of perimeter enclosure - depends on height of floor above ground
• Can increase system R-value by R1.0
Wood and Energy Efficiency – Lightweight Construction © FWPA 2011
Floor: Decrease sub-floor air flow
Decrease air flow – Cover ground with plastic– Reduced ventilation requirements
Source: BCA 2010 Volume Two Figure 3.4.1.2
Wood and Energy Efficiency – Lightweight Construction © FWPA 2011
Floor: Cavity barrier
Increases R-value of floor by at least R0.5
Wood and Energy Efficiency – Lightweight Construction © FWPA 2011
Floor: Insulation below the floor
Additional insulation below ground floor:– Insulate inside of sub-floor perimeter wall
• May be cheaper• Thermal connection maintained with ground (better for
hot conditions)
– Insulate under the floor• Foil integrated with flooring (e.g. R-Flor – no gluing
issues)• Under floor joists with plywood, foil etc• Bulk insulation
Wood and Energy Efficiency – Lightweight Construction © FWPA 2011
High Mass House
Solar Mass House
Wood and Energy Efficiency – Lightweight Construction © FWPA 2011
Energy Efficient Housing
• High mass house– Main features and limitations– Pending research
• Lightweight house– Main features and benefits
• Hybrid and combination houses
Wood and Energy Efficiency – Lightweight Construction © FWPA 2011
High Mass House: Main features
Main design features:– Zoned design with living rooms to the north and
bedrooms to the south. Main heating in living areas– A length-to-width ratio of approximately 1 to 1.5 on
the E-W axis– Cavity/solid brick and slab-on-ground construction– Ceiling and walls may be insulated (recommended
values vary with climate)
Wood and Energy Efficiency – Lightweight Construction © FWPA 2011
High Mass House: Main features
Main design features:– North facing windows, sometimes with a
recommended area as a function of floor area– No, or minimum glass facing east and west– Shading devices to windows during summer
• e.g. eaves projection, deciduous trees for north facing windows
• shutters etc. for east and west facing windows
Wood and Energy Efficiency – Lightweight Construction © FWPA 2011
High Mass House
To operate properly requires:– Clear exposure to north facing sun– Site that allows for building on East-West axis– Living room (and other) windows ‘unscreened’
during winter days to allow sunlight penetration– Construction method that allows for wall and
ceiling insulation
Wood and Energy Efficiency – Lightweight Construction © FWPA 2011
Thermal Mass
How much mass is required?– Suggested that 1,200 kg of thermal mass per m2
will produce a zero heating house in cold European climates (Vale and Vale 2000)
– Southwell, UK – 723 kg/m2 sufficient (Vale)– Bairnsdale, AUS – 580 kg/m2 sufficient
(Oppenheim) – More theoretical work needs to be undertaken for
temperate climates
Wood and Energy Efficiency – Lightweight Construction © FWPA 2011
Thermal Mass
Suitable when:– Climate is suitable
• Diurnal range > 8 degrees
– Site is suitable• Allotment is oriented and sized adequately
Wood and Energy Efficiency – Lightweight Construction © FWPA 2011
Wood and Energy Efficiency – Lightweight Construction © FWPA 2011
Diurnal Range
ZONE DESCRIPTION DIURNAL RANGE1 High humid summer, warm
winter Lowest diurnal (day/night) temperature range
2 Warm humid summer, mild winter
Moderate to low diurnal (day/night) temperature range. Can vary significantly between inland to coastal
3 Hot dry summer, warm winter
Significant diurnal (day/night) range
4 Hot dry summer, cool winter
High diurnal (day/night) temperature range
5 Warm temperate Low diurnal (day/night) temperature range near coast to high diurnal range inland
6 Mild temperate Low diurnal (day/night) temperature range near coast to high diurnal range inland
7 Cool temperate Low diurnal (day/night) temperature range near coast to high diurnal range inland
8 Alpine Low humidity, high diurnal range
Source: Your Home Technical Manual
Wood and Energy Efficiency – Lightweight Construction © FWPA 2011
Lightweight House
Wood and Energy Efficiency – Lightweight Construction © FWPA 2011
Lightweight House
• Structural framework supports the building• Other materials provide spatial separation and
infill• Great flexibility • Providing excellent operational environmental
performance
Wood and Energy Efficiency – Lightweight Construction © FWPA 2011
Lightweight Timber: Benefits
• Less sensitive to orientation and solar access• Northern orientation is not critical• Provides much more flexibility for sighting on
a block• Greater flexibility in design, layout and
internal zoning• Adaptable over time
Wood and Energy Efficiency – Lightweight Construction © FWPA 2011
Lightweight Timber: Benefits
• Reduced capital costs compared with mass house
• Ease of construction – no cut and fill on sloping blocks, easy installation of insulation in walls and ceiling.
• Reduced carbon footprint through whole life
Wood and Energy Efficiency – Lightweight Construction © FWPA 2011
Lightweight Timber: Cost effective
Source: Think Brick (2009) Wasting Energy. Available at http://www.thinkbrick.com.au/assets/documents/position_papers/PP2-Wasting-Energy.pdf
$20,0000 100 kWh/pa
Wood and Energy Efficiency – Lightweight Construction © FWPA 2011
Lightweight Timber: Cost effective and energy efficient
• Largest difference is 100 kwH per annum to heat/cool• Extra cost ~ $20 per year• Compare cost of construction:
– insulated double brick $52,000– insulated timber $32,000 – saving $20,000
• House life >1,000 years to pay for the difference• Enough to buy a big solar power system and make house
greenhouse neutral• Calculations don’t include the greenhouse gases emitted in
brick production or absorbed during tree growth
Wood and Energy Efficiency – Lightweight Construction © FWPA 2011
Lightweight Timber: Lower carbon footprint
• Total GHG emissions - 5 star
Insulated steel frame, brick clad, suspended
steel
Insulated steel frame, brick clad and concrete
slab
Insulated timber frame, brick clad and concrete
slab
Insulated timber frame, brick clad, suspended
timber
Insulated timber frame, timber clad, suspended
timber
Melb 137.088000000001 137.088000000001 131.04 127.008 120.96
Sydney 73.584 72.576 66.528 63.504 56.448
Brisbane 78.624 77.616 71.568 68.544 61.488
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30
50
70
90
110
130
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Wood and Energy Efficiency – Lightweight Construction © FWPA 2011
Lightweight Timber & Thermal Mass
The difference in thermal mass between standard new build masonry and insulated lightweight timber frame construction is not a significant factor affecting either thermal comfort or energy consumption, now or within the lifetime of the building.
Wood and Energy Efficiency – Lightweight Construction © FWPA 2011
Lightweight Timber: Lower carbon footprint
• GHG emissions reductions using timber
Wood and Energy Efficiency – Lightweight Construction © FWPA 2011
Wood is an insulator
Thermal image
Wood and Energy Efficiency – Lightweight Construction © FWPA 2011
Hybrid house
The heavy mass and lightweight house hybrid: • It’s not always a simple decision of either/or! • If site allows access to some northern sun,
mass can be incorporated in specific locations to use the solar heat in wintere.g. composite concrete/timber with lightweight timber-frame walls
Wood and Energy Efficiency – Lightweight Construction © FWPA 2011
Composite concrete/timber floor
Wood and Energy Efficiency – Lightweight Construction © FWPA 2011
Combination Lightweight House
+
Wood and Energy Efficiency – Lightweight Construction © FWPA 2011
Learn more about wood at UTAS
Centre for Sustainable Architecture with WoodGraduate Certificate in Timber (Processing & Building)• 4 units, part time, onlineAreas covered include:• Wood science• Design for durability and service for life• Timber as a renewable resource• Sustainable design and construction• Engineered wood products• International technologies and developments• Plus, selected topics of individual interestMore information: Associate Professor Greg Nolan (03) 6324 4478 or [email protected]
Wood and Energy Efficiency – Lightweight Construction © FWPA 2011
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