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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 occurs, 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.

That’s 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 described 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.

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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.

It’s 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 don’t 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!

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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 building’s 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!

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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!

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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 you’re 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.

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What is NatHERS

The Nationwide House Energy Rating Scheme (NatHERS) is an Australian initiative that provides energy ratings for new dwellings.

It aims to create energy-efficient, resilient, and comfortable homes for the future that cost less to run.

Here are some key points about NatHERS:

  • NatHERS provides a star rating out of ten based on an estimate of a home?s potential heating and cooling energy use.
  • The NatHERS scheme has been upgraded to provide world-leading measurement tools that the building sector can use to support the move to net zero emissions by 2050.
  • NatHERS can now rate the energy performance for the whole home including major appliances, solar panels, and batteries, in addition to the star rating for the building shell.
  • NatHERS provides a streamlined pathway to meet or exceed the new National Construction Code (NCC) 2022 energy efficiency requirements.
  • The minimum requirement for new houses and apartments is 7 stars (out of 10).
  • A new annual energy use budget will also apply, to account for a home?s major fixed appliances and any energy generated from solar panels/PV.
  • NatHERS is administered by the Department of Climate Change, Energy, the Environment, and Water on behalf of the states and territories.

For more information, you can visit the official NatHERS website.

Contact us for for help, assistance, questions or to arrange a NatHERS simulation or certificate.

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What is a Blower Door Test

A blower door test is a diagnostic procedure used to measure the airtightness of buildings.

It can identify air leakage and help improve energy efficiency.

During the test, a blower door fan is mounted into an external doorway, and either pressurises or depressurises the building to reveal unsealed cracks and openings through which air can enter or escape (infiltrate or exfiltrate).

This process is crucial for determining how much air leaks in or out a home, which can impact heating and cooling costs, comfort levels, and indoor air quality.

Professionals use this test to recommend improvements and ensure that heating and cooling systems are properly sized. The results of a blower door test can guide homeowners in making targeted upgrades to enhance their home’s energy performance and comfort.

Here’s how it works:

  • The blower door fan depressurizes the house by pulling air out, which lowers the indoor air pressure.
  • The higher outdoor air pressure then flows in through all unsealed cracks and openings.
  • A pressure gauge, called a manometer, measures the pressure differences inside and outside the home.
  • The rate at which air infiltrates the home is recorded, often in terms of Air Changes per Hour (ACH).
  • The test can also be conducted in reverse, with the fan blowing air into the house to create positive pressure. During the test, professionals may use an infrared camera or a smoke pencil to detect the specific locations of air leaks.

Blower door tests are important for several reasons:

  • They help reduce energy consumption due to excess air leakage.
  • They prevent moisture condensation problems and uncomfortable drafts.
  • They control the entry of outdoor contaminants, pests, and odours.
  • They assist in determining the proper sizing of heating and cooling equipment.
  • They indicate whether mechanical ventilation is needed to maintain indoor air quality.

If you would like to arrange a Blower Door Test or have any questions, please contact us!

ATTMA | Registered Air Tightness Testers – Australia (bcta.group)

ABCB Building Code Building Sealing Verification

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7 stars – BCA 2022

October 2023 we will need to achieve 7 stars for new homes.

Designers, Architects & Builders work out how long it takes from initial client meeting to getting DA for your past projects and see when you need to adjust designs for 7 stars.

It is going to be drastic!

Doing what you want and thinking insulation and some window upgrades will get the pass won’t work any more.

7 stars will probably mean;

  • Living areas and importantly windows in living areas face north
  • Waffle pod slabs
  • R2.5 wall insulation
  • R6.0 ceiling insulation
  • Insulating joists over garages & Alfrescos
  • Low e glass, ceiling fans & shade devices for cooling
  • Double glazing for heating

Windows will be the problem and result in very high expense!

Check your glass to floor ratio (area of windows in elevation divided by the floor area) works for a room or the whole house, up to 30% won’t be to bad, higher than this and it will be very expensive to achieve 7 stars.

Good thermal design has;

  • 50% of the north facade as glass
  • 15% of east & west facades as glass
  • 10% of south facade as glass

If you are not close to the above numbers this is where to start improving the design to achieve 7 stars at a lower cost!

If you would like assistance or advice with meeting the 7 star requirement, please get in contact with us!