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Eaves and thermal comfort
Building for the Australian Climate
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Passive House is a science-based building standard which takes into consideration the energy and health-based standards within the design and construction industry. There is a rigorous methodology in order to meet Passive House Certification – it is generally considered the toughest voluntary building standard in the world to achieve.
The high-performance building standard of Passive House (Passivhaus) started in Europe and the first Passivehaus was built in 1990.
The Passive House movement has grown in popularity across Australia. While the Australian Government continue their initiative in combating carbon emissions, legislation that require stricter standards in construction has a strong alignment with the Passive House Standard.
A Certified Passive House sets criterion for thermal comfort, minimum fresh air, reduction of air leakage, limits on heating and cooling energy consumption, and the total energy usage including appliances.
The Passive House Certification can be applied to new and existing buildings. The certification can be applied to all buildings and not just a ‘House’, the confusion comes from the German translation for ‘Building’ which is “Haus”.
The ability to apply the Passive House Standard for an existing building can be completed with the use of retrofits by the installation of Passive House certified components.
It's expected that a Certified Passive House building maintains comfortable internal temperatures through the year.
Temperatures must not exceed 25°C for more than 10% of the hours in the whole year.
Surface temperatures are taken into account as well. The internal surface of external walls and roofs must not reach below 1°C the indoor air temperature.
While the internal window surfaces must be less than 3.5°C of indoor air temperature.
There should not be any draughts because the internal air speeds will be low since there should be minimal differences between temperature for internal surfaces.
The minimum requirement for fresh air in a Certified Passive House will have a ventilation system that provides 30m3 of fresh air quality for every person each hour. You won't experience sale interiors because of this standard which gives a supply of freshness and good ventilation.
This is in reference to the air leakage standard for Passive House and a blower door test that will pressurise and depressurise the building. The air leakage will be limited to 0.6 air changes per hour at 50 Pascals pressure (ACH50).
This requirement takes into consideration the total energy consumption used for the building operation. It will include the heating, cooling, lighting, equipment, hot water, plug loads and more. The number of kilowatt hours per square meter will vary based on the level of certification and if there is usage of renewable energy for the building.
This is the amount of active heating and cooling input required to heat or cool a building.
The requirement is 15 kilowatt hours per square meter of treated floor area per year or 10 Watts per square meter peak load.
The difference for the space cooling energy demand will have a small allowance in kilowatt's for dehumidification.
The Passive House Planning Package (PHPP) is a powerful design tool used for designing low energy buildings. It is a mandatory tool used by Passive House Assessors that it used during all stages of development. It is the tool used in the certification of a Passive House Building.
At the core, the Passive House Planning Package (PHPP) is a collection of building physics algorithms. It was created by the Passive House Institute and is primarily used as a design, verification and certification tool.
The Passive House Planning Package contain worksheets in 4 categories:
|The Verification Category||Contains 2 worksheets which are Passive House Verification and PHPP Check.|
|The Heating Category||Contains 12 worksheets which are Climate, U-values, Areas, Ground, Components, Windows, Shading, Ventilation, Additional Ventilation, Annual Heating, Heating and Heating Load.|
|The Cooling Category||Contains 5 worksheets which are Summer Ventilation, Summer, Cooling, Cooling Units, Cooling Load.|
|The Primary Energy Category||Contains 16 worksheets which are Domestic Hot Water and Distribution, Solar Domestic Hot Water, PV, Electricity, Non-residential Utilisation, Auxiliary Electricity, Internal Heat Gains, Internal Heat Gains for Non-Residential, Primary Energy Renewable (PER), Heat Pump, Boiler, District Heating and Data.|
The Passive House Planning Package (PHPP) is not only used by Passive House Assessors, but it can also be used very early in the design process making it a powerful and necessary tool for Passive House Design.
With its holistic construction approach, the standard allows Certified Passive House Consultants with flexibility in design that is based on the building's usage and its location in order to achieve certification.
A Passive House building is designed with 5 key building principles in order to attain a quantifiable and strict level of energy efficiency with a specific comfort level to achieve the Passive House Design philosophy.
(Sourced from passivehausmed.com)
An airtight building envelope is an essential part of Passive House. With limited amounts of gaps within the building envelope this provides complete control in the improvement of thermal comfort and the internal environment.
2. Thermal Insulation
It's required to provide sufficient thermal separation between the heated & cooled internal and external environment. This will help with the thermal comfort and a reduction in condensation.
3. Mechanical Ventilation Heat Recovery
The purpose of this design principle is to create a self-sufficient system to achieve fresh air quality without constant reliance on opening and closing windows. The unit helps recover the hot and cool air and also filters air thats coming back inside the building. This lowers condensation and reduces the number of pollutants coming from the external environment.
4. High Performance Windows
The preferred choice for windows in a Certified Passive House are low-emissivity (a surface condition that emits low levels of radiant thermal energy) double or triple glazing with non-metal or thermally broken frames. They must be well sealed as well. The orientation of the windows will also dictate the sizing - this takes into consideration the balance between the entry of solar radiation entering during winter and summer.
5. Thermal Bridge Free Construction
It's important that the insulation penetration is kept at its absolute minimum. This requires a balance between the sufficient insulation thickness that is continuous. It's recommended to also use materials less conducive to heat.
If that isn't possible then incorporating material that doesn't conduct heat to seperate the two conducive material - this is referred to as a thermal break. This is an effort to reduce the number of thermal highways that would otherwise affect energy consumption and the risk of condensation.
With the Passive House Standard there are a range of benefits that homeowners, architects, builders and developers will receive using this approach.
A well-ventilated system delivers fresh & clean air supply continuous throughout the home. This removes stale air and the moisture and odours that accompany it.
|QUIET||Using recommended thermal insulation used in this building standard establishes firm noise separation between a Passive House building and the external environment. The high performance windows and tight sealing are great additions to noise reduction.|
|COMFORTABLE||With this superior standard, there are no hot or cold spot areas within the home. Temperatures stay consistent across all surfaces that create thermal balance which keeps occupants comfortable all year round.|
|AFFORDABLE||With up to 90% less energy used with the Passive House standard, occupants will find that their energy costs will be greatly reduced for the lifetime building operations.|
|SAFETY||You'll feel safe living in a Certified Passive House building because the thermal comfort remains consistent. In the event of a power outage during winter or summer, the building retains a comfortable temperature.|
With green initiatives becoming widely popular, financial institutions are incentivising homebuilders with reduced interest rates for mortgages.
FOR ARCHITECTS, BUILDERS & DEVELOPERS
The Passive House Standard will future-proof your building with its tough standards. With consideration to the government increasing their efforts and initiatives to reduce carbon emissions, you'll be secured that your building will meet future legislation.
|INCREASE SALES||A Certified Passive House has greater marketability value because it is a science-backed building standard. With increased concern for air quality, the Passive House standard with its strict requirement for fresh air quality and thermal comfort make it an attractive proposition.|
|HIGHER MARKET VALUE||Using recommended high quality components, insulation, windows and superior sealing brings a higher market value for a Certified Passive House.|
|QUALITY ASSURED||Due to its strict standard, a Certified Passive House Consultant will help reduce your project delays. They will carefully assess and examine each stage of the project to ensure that the building will meet requirements. Using a consultant early on in the project is a guaranteed way to maximise your projects efficiency.|
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