Thermal Performance

Author: admin_thermalperformance

  • Construction Update!

    We are underway with our Passive House for some lovely Owners!

    If you would like to drop by and chat and ask any questions about HIA Greensmart or Passive House please let me know!

  • What is WUFI?

    What is WUFI?

    WUFI analysis is a method used to simulate the hygrothermal (heat and moisture) behavior of building components. Developed by the Fraunhofer Institute for Building Physics, WUFI stands for “Wärme Und Feuchte Instationär,” which is German for “Heat and Moisture Transient”.

    Key Features of WUFI Analysis:

    • Dynamic Simulations: WUFI performs dynamic simulations of coupled heat and moisture transfer, providing realistic results under actual climate conditions.
    • Comprehensive Modeling: It accounts for vapor diffusion, capillary transport, sorption, and weather conditions like rain and solar radiation.
    • Risk Assessment: The software helps assess the risk of moisture accumulation, which can lead to mold growth and structural damage.
    • Material Properties: It uses standard material properties and easy-to-determine moisture storage and liquid transport functions.

    Applications:

    • Building Design: Used by architects and engineers to design buildings that are energy-efficient and moisture-resistant.
    • Wall & Roof construction methods: Helps designers & builder test or confirm the performance of proposed construction methods.
    • New Homes & Renovation Projects: Assists in evaluating the hygrothermal performance of buildings allow strategies to avoid condensation and mould risk.

    Would you like to know more about how WUFI analysis can be applied to your project? Contact us!

  • HIA – Webinar

    BASIX: Lessons in achieving 7 stars

    Hope you enjoyed the presentation, if you would like a copy please use the links below.

    HIA-Webinar-June-2024-Brad-HoadDownload
    permeance-calcDownload
  • HIA – Hunter Trade night presentation – Tuesday 28/5/24

    HIA – Hunter Trade night presentation – Tuesday 28/5/24

    Hope you enjoyed the presentation and learnt something!

    If you would like a copy of the presentation, please use the following download links!

    If we can help you on your project, please Contact Us!

    HIA Trade Night May 2024 Maitland Presentation – Brad HoadDownload
    Roof ventilationDownload
  • Building Wraps, Class 4, Water Control, Condensation, Reflective, What the?

    Building Wraps, Class 4, Water Control, Condensation, Reflective, What the?

    Hopefully this is educational so you can use as a reference to determine what is best for your situation.

    With the increasing building regulations and changes in the Building Code, we thought it was timely for a discussion on what it all means.  Different people/different terminology, they get called water control layers, pliable building membranes, wraps, sarking, weather resistant barriers WRB.

    If we start with the NCC or Building Code 2022;

    • Building Code Volume 1 2022
      • F3D3 Sarking refers you to AS 4200.1 & AS 4200.2.
      • F8D3 External wall construction pliable building membrane, talks about the AS, location, permeability, potentially a drained cavity, material open or closed to vapour & reflective wraps must have an air gap.
    • Building Code Volume 2 2022
      • H1D7 & H2D6 Roof and wall cladding refers you to the Housing Provisions
      • H1D9 Condensation management refers you to the Housing Provisions
    • Housing Provisions 2022
      • 7.5.2 Timber wall cladding (3) (c) compliance with AS 4200.1
      • 10.8.1 same as F8D3 above

    Terminology;

    • Air control membrane: A membrane installed to limit air transfer between each side of the membrane.
    • Primary insulation layer: The most interior insulation layer of a wall or roof construction.
    • Pliable building membrane: (from the BCA) A water barrier as classified by AS 4200.1. (from AS 4200.1) A material that is able to be folded back on itself without causing structural damage to the product that effects its material properties.
    • Thermal control membrane: a membrane with a surface emissivity (reflective insulation) and/or material R value (bulk insulation) intended to reduce heat transfer.
    • Sarking-type material: A material such as a reflective insulation or other flexible membrane of a type normally used for a purpose such as waterproofing, vapour management or thermal reflectance.
    • Vapour control membrane: a pliable building membrane designed to either allow or restrict the transfer of water vapour across the membrane.
    • Vapour permeance: The degree that water vapour is able to diffuse through a material, measured in ?g/N.s and tested in accordance with the ASTM-E96.
    • Water control membrane: a membrane intended to collect and discharge any water that penetrate a building envelope or cladding.

    AS 4200.1 Pliable building membranes and underlays;

    • Classifies membranes in several categories to ensure they are fit for purpose or suitable for the intended application.
    • Emmitance classification, (or how reflective the product is)
      • IR Reflective has an emittance of ? 0.05
      • IR Semi-reflective has an emittance of > 0.05 to ? 0.15
      • IR Non-reflective has an emittance of > 0.15
    • Vapour control classification, (how easy water vapour can pass through), permeance measured in ?g/N.s which is micrograms of water passing through a material per Newton second of force applied
      • Class 1 Vapour barrier 0 to <0.0022
      • Class 2 Vapour barrier 0.0022 to < 0.1429
      • Class 3 Vapour permeable 0.1429 to < 0.1403
      • Class 4 Vapour permeable 0.1403 to with no maximum
    • Water control classification, tested in accordance with AS/NZS 4201.4
      • Water barrier (it passed the test)
      • Non-water barrier (it failed the test)
    • Flammability classification, tested in accordance with AS 1530.2
      • Low, a flammability index ?5
      • High, a flammability index >5
    • Air control classification, (how air tight or resistance to air passing through it a product is) tested in accordance with ISO 5636-5
      • Air barrier Air resistance of ?0.1 MNs/m3
      • Non-air barrier Air resistance of ?0.1 MNs/m3

    So what is this really all that about? Condensation mainly and how to manage it, see our post on Condensation!

    It is important to note, you cannot stop condensation from occurring, you can take steps to reduce the likelihood of it occurring and plan to manage it with drainage & ventilation to assisting in drying out the materials to avoid mould and decay in your home.

    Next thing to talk about is direction of flow?, please read more here!

    So, the climate will determine the location of the wrap, membrane, control layer etc. we want to use these materials to either prevent passage of air or maximise the potential of it occurring, we dont want to use materials that are not compatible (say a permeable wrap with impermeable insulation or sheathing board).

    Remember;

    • Vapour control: usually a product that inhibits vapour movement to stop vapour from the outside.
    • Vapour permeable: to facilitate vapour movement from the inside to help dry the building out.
    • Thermal control: to keep things warm and not reach dew point temperature.
    • Air control: vapour is airborne moisture, hence if we control air movement we can prevent vapour getting into our walls & roofs to reduce the likelihood of interstitial condensation.
    • Controllable ventilation: can assist in removing vapour if used appropriately.
    • Smart or Intelligent membranes: that can restrict or facilitate the flow of vapour.

    The Building code talks about these concepts, some things are mandatory, some are only if you install etc.

    The proposed 2025 building code considers a requirement for a drained and ventilated cavity if you dont have a control layer. If its your licence or reputation I would suggest planning for control layers and a drained and ventilated cavity.

    What products are available and their characteristics, we have produced a list of materials for you to review & consider if correct for your application.

    Material-PermeanceDownload

    Who is involved in the process of designing, specifying and building?

    • Building Designer
    • Passive House Consultant
    • NatHERS Assessor
    • Blower Door Tester
    • Builder
    • Carpenter

    Ask them some questions about any of the above and see what they say, they may have an excellent understanding or may be new to risks associated with where the Building Code is taking us.

    If you dont get the responses you were expecting contact us to help you with your project.

    So what would we do or recommend;

    • The answer is well that depends on
      • What climate
      • What construction methods & materials
      • How you plan to manage Condensation, the strategy you will implement
      • The budget
      • Ventilation provided
      • Occupant behaviour
  • Understanding Condensation!

    Understanding Condensation!

    Condensation is the process where water vapor becomes liquid. It is the reverse action of evaporation, where liquid water becomes a vapor.

    Air contains some water vapour; warm moist air holds more vapour than cooler air.

    Condensation occurs in one of two ways:

    1. The air is cooled to its dew point.
    2. The air becomes so saturated with water vapor that it cannot hold any more water.

    The dew point is the temperature at which condensation happens, Air temperatures can reach or fall below the dew point naturally, often at night which will make building elements cold either at or below dew point.

    Thats why you see water droplets on the ground and around structures, and objects left outside in the morning.

    You are likely to notice condensation on your window frames when you have a warm shower on a cold morning (cold aluminium at or lower than dew point temperature and warm moist air = condensation).

    Condensation can also produce water droplets on the outside of a glass of cold water/beer. When warm air hits the cold surface, it reaches its dew point and condenses, leaving droplets of water on the glass.

    Clouds are masses of water droplets in the atmosphere, as more water vapor collects in clouds, they can become saturated with water vapor.  As the density, or closeness, of the molecules increase the clouds cannot hold any more water vapor. The vapor condenses and becomes rain.

    Cold air holds less water vapor than warm air. This is why warm climates are often more humid than cold ones: Water vapor stays in the air instead of condensing into rain. Cold climates are more likely to have rain, because water vapor condenses more easily there.

    When looking at the weather conditions you will see a term Relative Humidity expressed as a percentage of the maximum amount of water vapor the air could hold at that temperature, the higher number more vapour in the air.

    More Building related, we are worried about what is called interstitial condensation which is the same process describe above however occurs inside your walls or roof (usually hidden), this can lead to mould, mildew & decay hence can affect your health and the buildings structural adequacy.

    Most issues with interstitial condensation are caused by us (humans) showering, breathing, cooking, washing & drying clothes inside a house.

    As we increase building standards to produce buildings that are warm/cool (temperature difference from inside to outside) & airtight (no uncontrolled air movement, exfiltration/infiltration) we increase the risk of condensation occurring, so we need to be very aware of the materials we specify and how we construct buildings.  i.e. vapour open, vapour closed, what ventilation, what ACH or permeability we are expecting and if condensation does occur how does the building drain it out and how well/quickly the products dry out.

    Contact us if you would like further information or help with a project.

  • What is meant by Direction of Heat Flow?

    What is meant by Direction of Heat Flow?

    Heat flow or Heat transfer, is the movement of thermal energy from a region of higher temperature to a region of lower temperature. This process continues until thermal equilibrium is reached, that is, until the temperatures in both regions become equal.

    Put in simple terms heat flows from something that is hot to something that is cold (elements loose heat not gain cold).

    There are three main ways heat flows:

    1. Conduction: This is the transfer of heat within a solid or between solids in direct contact. The heat flows from the hotter part to the cooler part. Examples would be direct fix cladding transferring solar radiation to the internal environment or a window exposed to the internal and external temperatures conductive heat loss through the window frame.

    2. Convection: This is the transfer of heat in fluids (liquids and gases) where the heated fluid rises and the cooler fluid sinks due to differences in density, setting up a circulation pattern known as a convection current. This regularly gets referred to as stack ventilation or hot air rises.

    3. Radiation: This is the transfer of heat in the form of electromagnetic waves, primarily infrared radiation. Unlike conduction and convection, radiation can occur in a vacuum, such as the heat from the Sun reaching Earth. In building world we use a term thermal mass to describe the ability of a material to hold heat, e.g. solar action through the day will allow the thermal mass to gain heat and then as the air temperature drops at night it radiates the heat back to keep us warm.

    Its important to note that while we often talk about heat flowing, it is actually the energy that is moving, not the material itself (except in the case of convection).

    So if it is energy moving think about your power bill at home! We will use the words heat loss, this is another ways of saying wasting money.

    In building world when describing where a control layer (insulation layer or air barrier) should be installed you will hear people say on the warm side this is talking about the direction of heat flow (hot to cold) and is dependant on your climate;

    • If we are talking about bulk insulation it is best located as close to the warm side of the building envelope.
    • If we are talking about an air barrier that restricts air movement, then we want it on the warm side of the building envelope.
    • If we are talking about a vapour barrier that inhibits moisture movement, we want it on the warm side.
    • If we are talking building materials and in a cold climate we want to keep things warm so they dont reach dew point temperature, we want to reduce or avoid thermal bridging to avoid elements getting cold and reaching dew point temperature.
    • Hot humid climates, the warm side is usually on the outside, hence we are trying to stop heat getting in, trying to stop vapour from the outside, with air conditioning keeping the building cool, there is a high risk of interstitial condensation. Vapour or Air barriers on the outside of the building envelope will reduce the risk.
    • Cooler climates the warm side is usually on the inside, if it is somewhat airtight the vapour level will be higher on the inside, hence temperature or vapour is trying to get out of the building. Showering and breathing will add moisture vapor to the air, there is a high risk of this vapour going through plasterboard and condensating within the walls. We want Vapour or Air barriers on the inside of the building envelope to stop the potential of this occurring.
    • Temperate climates can be in both directions, usually heating is more dominant hence both heat flow and the vapour drive will be from the inside to the outside similar to cooler climates.

    Using the BCA to help the discussion, review BCA Volume 1 J4D4 Roof & Ceiling Construction

    • Climate zones 1 to 5 (middle to top of Australia) it says downward heat flow we are adding R value to stop downward heat flow or stop the heat getting in (heat gain).
    • Climate zone 6, (more the bottom of Australia) it says downward heat flow we are adding R value to stop downward heat flow or stop the heat getting in.
    • Climate zones 7 & 8 (Tasmania & Snow regions) ) it says upward heat flow we are adding R value to stop upward heat flow or stop the heat getting out (heat loss).

    If you would like to know anything further, please contact us here!

  • What is a Building Envelope?

    A building envelope is the physical barrier between the conditioned (internal) and unconditioned (external) environment of a building. It includes the floors, walls, windows & doors, ceiling & roof.

    The building envelope contains three main layers or barriers;

    1. Water Control Layer or Weather Barrier (WRB)
    2. Thermal Barrier or primary insulation layer
    3. Air Barrier (IAB)

    Depending on the design, the location, materials specified and how well the building is built will determine how well your building envelope performs.

    The building envelope plays a crucial role in a buildings energy efficiency. In winter, it helps prevent the transfer of heat from inside to outside (heat loss), and during summer it keeps the cool air inside (saving the occupant $) and reduces the heat coming through windows (heat gain).

    Think of it like;

    • Weather barrier keeps the rain & wind out.
    • Thermal barrier keeps the heat in with bulk insulation and the heat out with reflective insulation.
    • Window shading & types of glass work with the thermal barrier.
    • Air barrier stops uncontrolled air movement which keeps the internal temperate comfortable by reducing warm air out or cold air in.

    If you would like assistance with your project, please what services we can provide!

  • Group Homes, Class 3 & BASIX

    Group Homes, Class 3 & BASIX

    Is a BASIX Certificate required for a Group Home?

    Well yes & no (glad that clears it up)! it depends on your Certifier, hence they are more than likely going to require one.

    The BASIX website provides the following advice Alternative assessment – Large boarding house | Planning Portal – Department of Planning and Environment (nsw.gov.au). This states a boarding house or more than 12 people or more than 300m2 is NOT a Basix development.

    You will note that BASIX refers to the Environmental Planning & Assessment Regulation.

    The EP&A Regulation does not specifically refer to a Group Home.

    Under the BCA a group home is a Class 3 building i.e. boarding house (unrelated people).

    BASIX advises specifically for boarding houses (but doesn’t use the terminology class 3).

    The EP&A Regulation uses the terminology hotel, motel, boarding house, hostel or co-living housing and then adds the BCA conditions of more than 12 people or more than 300m2.

    Good luck!

    it will come down to the individual Certifier and the interpretation of group home verse co-living housing.

    Co-living housing

    Co-living housing was introduced to the NSW planning system when the Housing SEPP was made in November 2021.

    Under the Housing SEPP, the definition of co?living housing:

    • is subject to similar built-form development standards as boarding houses
    • must provide a primary place of residence for all occupants it may not be used for short-term tourist and visitor accommodation
    • may have as few as 6 private rooms (but most co-living housing developments will typically have about 30 to 40 private rooms)
    • must provide indoor and outdoor communal space for residents to relax and socialise
    • must have a manager, who will be responsible for implementing the plan of management for the property. The manager does not have to be always on site but must be contactable by phone 24/7.

    Sounds like a group home to me, but hey some will interpret it differently!

  • What is a BASIX Certificate?

    What is a BASIX Certificate?

    A BASIX (Building Sustainability Index) Certificate is a document generated online that identifies the sustainability features required to be incorporated in the building design.

    BASIX aims to create more comfortable and cost-efficient homes by reducing greenhouse gas emissions and water consumption.

    BASIX covers four topics:

    1. Water: The water section of the BASIX assessment examines the water efficiency of the appliances and fixtures, the design of the landscaping, and the use of alternative water sources in the development.

    2. Thermal Performance: The thermal performance section of the BASIX assessment examines the design and materials used in the building to reduce the need for artificial cooling and heating to keep the home comfortable. A NatHERS Certificate can be used to meet the requirements of the thermal performance section.

    3. Energy: The energy section of the BASIX assessment examines the energy efficiency of the appliances and equipment, and the use of alternative energy sources in the development.

    4. Materials: The material section of the BASIX assessment examines the embodied energy of the specified material and encourages less carbon intensive material to be used in the development.

    The targets or requirements to pass change depending on location, climate & fuel sources selected.

    If youre building a new home, undertaking renovations of $50,000 or more, or installing a pool or spa of more than 40,000 litres, you will need a BASIX certificate. Talk to Thermal Performance if you need assistance with a BASIX certificate.