The presentation addresses the thermal comfort requirements of the NSW Building Sustainability Index (BASIX) and how lightweight wood-based construction systems can be easily used to meet these requirements. Emphasis is placed on simple techniques to insulate walls, roofs and sub-floor areas of suspended floors for new construction as well as alterations and additions. The presentation will highlight cost effective design and building details, ventilation issues and smart use of thermal mass.
1. Wood and Energy Efficiency Lightweight Timber Framed Construction and NSW’s BASIX Thermal Comfort
2. Learn more about wood at UTAS Centre for Sustainable Architecture with Wood Graduate Certificate in Timber (Processing & Building) 4 units, part time, online Areas 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 interest More information: Associate Professor Greg Nolan (03) 6324 4478 or enquiries@arch.utas.edu.auwww.csaw.utas.edu.au
3. 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
4. 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
5. 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
6. Thermal Properties of Wood 1calculated based on values and method provided in BCA 2010 Volume One Specification J1.2 Table 2a.
14. 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
15. 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
17. 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
19. Energy Efficient Housing High mass house Main features and limitations Pending research Lightweight house Main features and benefits Hybrid and combination houses
20. 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)
21. 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
22. 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
23. 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
24. Thermal Mass Suitable when: Climate is suitable Diurnal range > 8 degrees Site is suitable Allotment is oriented and sized adequately
28. Lightweight House Structural framework supports the building Other materials provide spatial separation and infill Great flexibility Providing excellent operational environmental performance
29. 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
30. 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
31. Lightweight Timber: Cost effective $20,0000 100 kWh/pa Source: Think Brick (2009) Wasting Energy. Available at http://www.thinkbrick.com.au/assets/documents/position_papers/PP2-Wasting-Energy.pdf
32. Lightweight Timber: Cost effective and energy efficient Largest difference is 100 kwHper 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
34. 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.
37. 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
40. Learn more about wood at UTAS Centre for Sustainable Architecture with Wood Graduate Certificate in Timber (Processing & Building) 4 units, part time, online Areas 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 interest More information: Associate Professor Greg Nolan (03) 6324 4478 or enquiries@arch.utas.edu.auwww.csaw.utas.edu.au
To operate properly, it requires:clear exposure to the sun on north facing windows for living rooms (attractive views in other directions may compete with this requirement or solar access may be restricted by vegetation or buildings)a site that allows for a long rectangular building on the East-West axis (to allow large north-facing façade & windows)householders who are prepared to leave living room (and other) windows ‘unscreened’ during winter days to allow sunlight penetration (this may conflict with privacy considerations, especially in denser developments)a construction method that allows for wall and ceiling insulation (it is difficult to place insulation in cavity brick walls
Lightweight timber framed construction is very cost effective. And it’s not just the timber industry saying that. This graph, in a report by Think Brick based on research by the University of Newcastle shows the cost of different external walling systems with the differences in annual energy consumption. The differences they found in this study, which we don’t agree with by the way, are very minor. However the differences in costs of construction are huge