Residential air tightness testing

Can a building or a home be too airtight?

Some builders are concerned with building homes too airtight. Some reasons they give are:

Humans breathe. Your building also needs to breathe.
We don’t want people suffocating in our homes/buildings. You need to get fresh air from somewhere.
We don’t want to have to install a heat recovery (HRV) or energy recovery (ERV) ventilation system if we build too tight.
If I am going to naturally ventilate my building, why do I need to worry about air leakage?
We don’t want our homes or buildings to grow mould.

To begin with, each of these concerns arises from of lack of ventilation, not airtightness. Air leakage is NOT ventilation. So let’s go back to basics: what is ventilation?

Ventilation is the intentional introduction of air from the outdoors into a building. It can be natural or mechanical. In apartments, it is highly recommended that you consult a fire engineer, and consider a pressure relief strategy in the event of a fire outbreak inside the building envelope.

Natural ventilation is the flow of air through open windows, doors, vents, and other planned building envelope penetrations, and it is driven by natural forces.

Mechanical ventilation is the intentional movement of air into and out of a building using supply or exhaust fans.

For ventilation to be effective we need to consider the quantity, the quality, and the distribution of air into an occupied space. Can air leakage satisfy these three factors? Some things to consider:

Air from leaks is not filtered. It may come from a mouldy, dusty, or vermin-infested building cavity.
There is no way to easily temper the air coming in, so it brings the temperature, humidity or dryness of the outside with it.
Air leakage leaves you at the mercy of the weather. On windy, hot, or cold days, lots of air exchange results, but on mild, calm days, there is very little transfer.
Because you can’t locate or control all air leaks, it’s very hard to make sure each room gets the right amount of fresh air.

Mechanical ventilation is guaranteed fresh air from a strategically-located source, no matter what the weather is.

There is no way to compare air leakage with ventilation! Not only does infiltration fail to meet ventilation needs, it has additional harmful effects to your building and the health of its occupants.

Condensation in wall systems and inside internal surfaces in a building.

When infiltration brings air from outside, it can create localised cold spots in walls, floors, and ceilings. These have the potential to create condensation, which can lead to mould growth or stains on finishes. Unchecked, condensation can lead to rotting or corrosion of materials, causing structural damage. It also makes a more inviting habitat for a termite infestation.

These issues may lie undetected until it’s too late. The mould that forms inside walls, with infiltration, can distribute mould spores through your home, and you cannot clean or maintain these surfaces inside your building fabric.

For buildings that are designed for natural ventilation, the intentional openings should be fitted with condensate drains and be constructed using water-resistant materials. The location of these openings should be accessible for cleaning and maintenance. The most common example is mould that forms on leaky windows, which can be cleaned easily.

Reduces the performance of your insulation system.

When insulation materials are rated in the laboratory, they are under controlled conditions with no air moving through the test sample. In the real world, air leaks can pass air through insulation, which substantially reduces insulation performance in two ways:

Direct bypass – air leakage can pass right around both rigid and fibrous insulation
Wind washing – air can pass through bulk insulation material itself, disturbing air pockets trapped by the fibres and stealing the heat it is meant to retain

Unwanted distribution of pollutants throughout the building.

In leaky buildings, pollutants can distribute through a building via unintentional gaps and cracks. This can create problems ranging from minor nuisances such as odours to more serious issues such as carbon monoxide from a garage or car park. Most dangerously, they are a potential path of smoke in the case of a fire.

Other issues from air leakage

Air leakage in larger buildings can also contribute to noise infiltration and noise production from whistling under windy conditions.

Lastly, any hole to the outside, garage, underground car parks or other unconditioned spaces serve as easy paths for CO or other pollutants and ants, cockroaches, spiders, mites, mice, and other unwanted guests. Sealing up these paths is the cheapest and first method of pest control.

To address concerns for airtightness in homes:

When someone says that a house needs to breathe, ask them to close their eyes and… breathe. When they take a deep breath in, air only enters through their mouth or nose. They don’t need air to come in any other way. The same is true for a house. Breathe only through openings made for that purpose.
You cannot build a building so tight that it is dangerous when you include ventilation.
For typical homes, providing basic ventilation can be inexpensive and easy. A simple continuously running remote-mounted extract fan is quiet and energy-efficient.
There is no good argument for airflow through walls. Truly fresh air should be filtered, volume-controlled, and distributed by design. Getting the fresh air from a mouldy wall cavity is not healthy or reliable.
To reduce condensation and mould potential, add simple continuous mechanical ventilation and pay attention to thermal bridges in the construction of the home. Condensation is a complex phenomenon; increased ventilation alone may not solve the problem. You can experience condensation and mould on a carport soffit that has no walls.

Air Barrier Integrity Auditing

When trying to build airtight, the real magic is NOT the air-tightness testing itself, it’s actually the Building Design, continuous QA (Air Barrier Integrity Auditing) during construction and ensuring an “Air-tightness Champion” has been appointed by the builder.

The key features of conducting air barrier integrity auditing are:

Locating areas of concern with exact locations of the issues.
Verification of building materials being used, that will enable an air barrier that lasts
Timely reporting of the issues, so that remediation can be undertaken before finishes
Capturing photographs of remediation works
Confirming or finding issues in building facades/junctions for a continuous air barrier using Ultrasonic technology.
Recommendations of remediations required, with materials/products that comply with the Australian Building code.

If a QA process is not conducted regularly at key intervals during construction,

- airtightness targets can become a very expensive exercise,

remediation works that happen after construction can have the potential to not last the test of time,
or remediation works may not even be possible due to safety.

Location, Location, Location

Commercial Buildings can be large and complicated, so it is important, that plans are marked up with problematic details, if trades cannot find issues, they just won’t fix them. If issues cannot be relocated to verify remediation, then the whole process of air barrier integrity auditing is rendered ineffective and pointless.

Verification of building materials.

In some circumstances, building materials specified for the air barrier may be inadvertently costed out, or supplied with an inappropriate product. Certain tapes or sealants may not be compatible together or may react undesirably when exposed to environments during construction. It’s important to catch these issues during construction so that they can be repaired in a timely manner before finishes.

Report turnover

Projects can move extremely fast, and it is not uncommon for the fit-out to begin before service risers are complete. Once an inspection is conducted, a report must be issued with all the location details marked off an up to date floor plan, recommended fix and dimensions of the issue, with the direction of how the air barrier should be continued.

Photo evidence

Photo’s of issues should be marked up to clearly articulate to trades the whole that must be closed in. Airtightness is not always obvious.

Troubleshooting during construction

Troubleshooting and confirming air leakage through the air barrier when the building is under construction is difficult. There are technologies available to help confirm non-obvious gaps in building elements. Ultrasonic sound auditing can add significant value.
An array of ultrasonic transmitters which generate ultrasonic waves are set up on the outside. This makes it possible to find gaps in curtain wall facades, leaks through building elements, door frames/window frames and window/door seals, even ducts and plenums.

The ultrasonic detector picks up ultrasound via a microphone and converts the inaudible ultrasound into an audible frequency and in some circumstances overlays the frequency emission location on top of a visual image with a representative highlighted colour. A visual representation is bundled together using a directional array of receivers capable of picking up ultrasonic sound waves while suppressing other noise and outputting onto an image. Because ultrasonic waves are so directional, from the emission source surveys can be undertaken on partly completed wall details. When auditing ultrasonic sound gets louder the closer you get to the leak and is quickly muffled as it moves through the air. The ultrasonic leak detection can pinpoint even the smallest leaks, during a partly constructed building, which is the most economic time to organise a solution.

Recommended Remediation

During construction, drawings sometimes miss air barrier continuity. Different materials that make up the air barrier have different surfaces and therefore different products need to be used depending on the circumstances to ensure the longevity of the air barrier over the life of the building.

Air Barrier Integrity Auditing, is a critical part of building commissioning, combination with an Airtightness champion who is an integral part of the construction team, coupled with good building design and detailing, airtightness targets of the likes of Passive house or even more stringent can be achieved as economically as possible.

Vapour permeable wall wraps, the devil is in the detail

There are wall wraps, and then there are wall wraps. Different users have different requirements and expectations for what they want their wrap to do.
In most cases we should, and can expect modern nonwoven textile wraps to control:

Water – Stop rain from getting into the building during construction before cladding installation – Prevent damaging to insulation/internal services and finishes that aren’t designed to be exposed to the elements. Avoiding health and structural related damage
Air – Once the building is finished air can impact/exacerbate water ingress, moisture build-up from water vapour, temperature ingress, sound ingress and fire/smoke pathways.
Water Vapour – Condensing water vapour and high humidity can lead to health and structural damage in completed buildings.
Not to Contribute to fire combustibility – limiting the amount of combustible material in key parts of our builds.

- Some woven glass/aluminium laminates are deemed to be non-combustible by the building code
- vapour permeable airtight wraps and plastic/foil laminate wraps usually are of low flammability rather than being non-combustible.

Sometimes we may be forced to compromise on some of these control layers, but we also need to pay attention to the minimum requirements in the NCC.

Things have become easier since the NCC 2019 which extended the list of materials that may be used wherever a non-combustible material is required or where the requirement to be non-combustible does not apply.

C1.9 Non-combustible building elements

(a) In a building required to be of Type A or B construction, the following building elements and their components must
be non-combustible:
(i) External walls and common walls, including all components incorporated in them including the facade covering,
framing and insulation.
(ii) The flooring and floor framing of lift pits.
(iii) Non-loadbearing internal walls where they are required to be fire-resisting.
(b) A shaft, being a lift, ventilating, pipe, garbage, or similar shaft that is not for the discharge of hot products of
combustion, that is non-loadbearing, must be of non-combustible construction in-
(i) a building required to be of Type A construction; and
(ii) a building required to be of Type B construction, subject to C2.10, in-
(A) a Class 2, 3 or 9 building; and
(B) a Class 5, 6, 7 or 8 building if the shaft connects more than 2 storeys.
(c) A loadbearing internal wall and a loadbearing fire wall, including those that are part of a loadbearing shaft, must
comply with Specification C1.1.
(d) The requirements of (a) and (b) do not apply to the following:
(i) Gaskets.
(ii) Caulking.
(iii) Sealants.
(iv) Termite management systems.
(v) Glass, including laminated glass.
(vi) Thermal breaks associated with glazing systems.
(vii) Damp-proof courses.
(e) The following materials may be used wherever a non-combustible material is required:
(i) Plasterboard.
(ii) Perforated gypsum lath with a normal paper finish.
(iii) Fibrous-plaster sheet.
(iv) Fibre-reinforced cement sheeting.
(v) Pre-finished metal sheeting having a combustible surface finish not exceeding 1 mm thickness and where the
Spread-of-Flame Index of the product is not greater than 0.
(vi) Sarking-type materials that do not exceed 1 mm in thickness and have a Flammability Index not greater than
(vii) Bonded laminated materials where-
(A) each lamina, including any core, is non-combustible; and
(B) each adhesive layer does not exceed 1 mm in thickness and the total thickness of the adhesive layers

NCC 2019 Building Code of Australia – Volume One Page 67

In the Latest NCC 2019 some of the key additions that will help enable the construction of walls that can effectively manage water, air, vapour and thermal control are these materials:

Sarking-type materials that do not exceed 1 mm in thickness and have a Flammability Index not greater than 5.
Gaskets
Caulking
Sealants
Thermal breaks associated to glazing systems.

Prior to the NCC 2019 revisions, there was a conflict between meeting an:

air tightness target leakage rate,
water barrier and
vapour control when only
non-combustible elements could be used in type A and type B wall systems.

There never has been a wrap product available that meets the NCC requirement for non-combustibility, while at the same time as being an effective air and water barrier, combined with sufficient vapour permeability for use in cool and temperate climates.

Current products on the market today that are deemed non-combustible are made from pure aluminium foil laminated, an adhesive layer and a woven glass cloth. Aluminium Foil when reinforced can be very airtight, but these products are also extremely vapor tight (Incapable of allowing moisture vapour to escape/permeate to outside).

To get around this issue of vapour control, some aluminium foil based products in an attempt to make them vapour permeable have holes punched into them.

This is a hard balance to strike. Making holes in a material compromises its effectiveness as a water and airtight layer. There is a reason as to why its hard to find an umbrella for sale that has holes pre-punched in it.

On the other side of the equation, with aluminium foil type wraps, if the holes are so small and infrequent, these types of products still struggle as a vapour permeable underlay. Like single glazed glass windows, aluminium foil is a non-porous material and it is prone to condensation forming on its surface. Within the space of a year we have seen perforated deemed non-combustible sarking layer where quoted vapour permeance values have swung wildly from the realistic to the implausible and back again to just mildly astonishing.

Well established polyolefin textile air and watertight vapour permeable wraps can provide a far superior vapour permeability performance without compromising other important features.

If following a deemed to satisfy path using NCC 2016 for non-combustibility of wall elements then in most cases this will inevitably require some compromise of water tightness, air tightness or vapour permeability. The only realistic option to date has been to insulate external the non-combustible sarking, us a non-combustible vapour permeable sheathing board, or follow a performance solution / fire engineered pathway.

Moving on… Looking at the requirements of a water barrier under the AS4200.1: 1994 code for sarking you can see that almost all perforated aluminium based materials are unhelpfully classified as:

“Water Barrier – Unclassified.

6.4 Water barrier The water barrier classification shall be neither high or unclassified. The resistance to water penetration shall be determined, as required, by the method described in AS/NZS 4201.4. as follows:

(a) High The material shall only be classified as high if it passes the test,

(b) Unclassified When the material is not classified as high, it shall be unclassified.

In terms of AS4200.1 : 1994 classification, if a datasheet is reporting a product to be “unclassified”, it means it has not passed the water barrier test which is a simple 10cm standing head of water test.

The current version of AS4200.1: 2018 is more helpful to the user and the product will now be defined as:

“Water Barrier – Non-water barrier”

5.3.5 Water control classification

The water control classifications shall be determined as follows;

(a) Water barrier – if the membrane passes the test specified as AS/NZS4201.4.

(b) Non-water barrier – if the membrane fails the test specified in or has not been tested to AS/NZS 4201.4.

How then have things changed for classification of vapor permeance?

In the 1994 version of the code there was no classification of vapour permeance. Products were either a low, medium or high classification as a vapour barrier. Just because a material wasn’t a particularly fantastic vapour barrier does not imply that it is sufficiently vapour permeable.

The 2019 NCC Condensation Management DTS requirements for climate zones 6,7 & 8 now requires a vapour permeable membrane, In the updated 2017 version of A4200.1 vapour barrier and vapour permeable membranes using table 4. See below. (Southern Australia and Alpine areas)

We should only be seriously using class 4 products with a vapour permeance of >1.14µg/N.s Class 3 seems like a bit of a hangover from the old building code to cover the old “perforated” foil wraps with holes punched into them(Perforated sarking).

When considering that a typical paper faced plasterboard has a permeance of around 2.0µg/N.s then it is a good rule of thumb to ensure the external wrap is at least as permeable (>2.0µg/N.s ) as the interior plasterboard lining. In order to control moisture successfully inside a wall system the vapour permeability of materials are increasingly vapour permeable toward the outside of the wall system.

TABLE 4

VAPOUR CONTROL MEMBRANE (VCM) CLASSIFICATION

Vapour permeance (see Note)

μg/N.s

Class	VCM Category	Min. (>=)	Max. (<)
Class 1	Vapour Barrier	0.0000	0.0022
Class 2	Vapour Barrier	0.0022	0.1429
Class 3	Vapour Permeable	0.1429	1.1403
Class 4	Vapour Permeable	1.1403	No max.
	ASTM-E96 Method B Wet Cup - 28 C 50%RH

NOTE: Vapour permeance is the inverse of vapour resistance. It shall be calculated as follows:

Vapour permeance μg/N.s = 1/(Vapour resistance MN.s/g)

Almost all building wraps are combustible, and the caloric value (the heat produced by the complete combustion) of wraps is quite small compared to the volume of materials that are non-combustible in a wall system.

From NCC2019 building wraps/membranes that are less than 1mm thickness with a flammability index of no greater than 5 used wherever a non-combustible material is required. This means you can now have your cake and eat it. For applications using NCC 2016, in most cases, your only solution is to discuss with your fire engineer about a performance solution.

Using Vapour Permeable Wraps at the Bottom of wall detailed with air tightness.

Getting an air tight barrier at the bottom of a brick veneer wall system using damp-course as your air barrier, with an overlap from a vapour permeable wrap.If you have any questions or about this contact please contact us.

FAQ Air tightness and ventilation

Frequently Asked Questions

Healthy Buildings

Why could indoor air quality be a problem in our homes?

Our homes and offices may be becoming ‘tighter’ with less free air movement with the outdoors. This is due to:

Improvements in building techniques and styles (concrete slab-on-ground construction) producing ‘tighter’ buildings;
Changes to building regulations to increase energy conservation (insulation and design regulations);
Demand for greater comfort during very warm or cold periods;
Need to reduce the intrusion of external noise and/or air pollution;
Increased demand for privacy; and
Increased demand for security.

Indoor Air Quality Facts

The U.S. EPA. studies show that indoor air can be 2 to 5 times more polluted than outdoor air.
“Occupants of new Australian homes may be exposed to up to 20 times the maximum allowable limits of indoor air toxics, an Australian first study has found.” (CSIRO media release)
We require between 8,000 and 10,000 litres of air each day.
We spend more and more of our time indoors. More than 90% according to the C.S.I.R.O.
Moisture, a key ingredient in indoor air pollution, is generated mainly from our activities within the home. These activities include: Cooking, Washing, Bathing, Respiration and Perspiration ( adults add about 2 litres of moisture to the airstream everyday), etc.
Outdoor pollutants (car fumes, pollen, dust,) can also enter the home and become concentrated there.

Why is it important to ventilate?

Ventilation is the key to improving indoor air quality!

“Indoor air quality is influenced by two major components: the amount and quality of outdoor air getting in, and indoor sources of emissions.”*

Contributing factor to indoor air quality	Percentage of cases
Inadequate ventilation	52
Contamination from inside the building	16
Contaminants brought in from outside the building	10
Microbiological contaminants	5
Building material contamination	4
Cause not determined	13

The above information comes from the Australian Government Air Toxics website.

Ventilation assists in controlling relative humidity which:

controls dustmite and molds
reduces lifetime of airborne viruses and bacteria
controls off-gassing from building materials and furnishings.

Ventilation dilutes and removes harmful airborne pollutants, and

Ventilation replenishes oxygen levels:

to provide adequate levels for occupants to breathe
and to ensure gas fired appliances burn correctly.

Why “Natural” ventilation (using windows and doors) doesn’t always work

The weather is unpredictable, ie. too windy, no breeze, too cold or hot,
Poor location of doors and windows often restricts good cross ventilation,
Indoor temperature control is lost when windows and external doors are left open,
Windows don’t filter (dust, pollen, outdoor pollution and noise), and
Home Security can be compromised.

What causes indoor air pollution?

Air pollution in the home is often misunderstood or underestimated.

Since the mid nineteen eighties, building scientists have had to come to grip with the terms Sick Building Syndrome and ‘Building Related Illness’. The first complaints relating to illnesses associated with the indoor environment came out of the workplace and included problems such as migraines, nausea, sinus problems or even worse.

Now, these same scientists are beginning to focus on residential buildings and they are finding even worse pollution problems right inside the home. What is supposed to be a safe haven for the family, has turned out to be an extremely unsafe environment in terms of occupant health.

Close to 250 chemicals are used in the building materials that make up a house. With the introduction of new household products like cleaners, personal care products and simple things such as ‘air fresheners’, we are building up a substantial arsenal of chemicals in our homes. Warm and humid conditions in the home allow a phenomenon known as ‘off-gassing’ to occur. Chemicals such as formaldehyde and Volatile Organic Compounds which are in many of the building products in the home leach out of the products in a gaseous form creating a toxic, chemical soup we live in, day in and day out.

To help you identify the pollutants inside your home, see the Pollution Sources List below.

moisture	pressed wood furniture and cabinetry	humidifiers
insect repellents	dry-cleaned clothes	house dust mites
personal care products	air fresheners	stored fuels
paint supplies	panelling	woodstoves
tobacco smoke	carpets	pressed-wood subflooring
drapery	open fireplaces	household chemicals
moulds and mildews	plant soil	rubbish bins
unvented clothes dryers	pesticides	and
fixed vents which allow pollen, dust, humidity, noise and other pollutants to enter from outside.

Do moulds and fungi increase our risk to respiratory illnesses?

From ABC Radio National an interview by Rae Fry of the Health Report with the head of the Environmental Division of Finland’s National Public Health Institute – Dr Aino Nevalainen.

” Now to a subject that doesn’t get a lot of attention, probably not as much as it should. The quality of indoor air. Most of us spend 80% to 90% of our time inside, but how much do we know about the effects on our health?

A big study has just been done in Finland about fungi and mould in indoor air. And the researchers found that the rates of respiratory conditions, like sinusitis and flu are affected. It’s not older buildings with that patch of rising damp in the corner, that we’re talking about. In modern buildings, moisture can get trapped inside walls where you can’t see it; and in houses these days, there’s so much water going in and out, for showers and laundry, that leaking pipes can be a problem. ”

Read the full interview on the ABC Radio National Health Report 30/8/99

Why are Relative Humidity (RH) levels significant in your home?

It is accepted that the indoor relative humidity often exceeds outdoor relative humidity. This is mainly due to activities within the home ( showers, cooking, washing, dryer, etc)

The optimum RH zone for the wellbeing of the building as well as the health of its occupants is between 30 and 55 % relative humidity.

Outside of this range the growth of bacteria, fungi, viruses as well as increased chemical off-gassing and ozone production is promoted.

Allowing outside air to enter the house through fixed vents (uncontrolled ventilation) or the use of windows and doors will only improve humidity levels in the home occasionally. However, the relative humidity level of the outside air is often too high or too low to create a healthy indoor environment. (see RH Levels Chart below for Sydney and Melbourne.)

To add to these problems, on still days insufficient airflow occurs and so pollution levels can increase in the home. Windy days could provide sufficient air changes to remove indoor pollutants, however comfort and energy costs can also be compromised by outdoor drafts reducing the effectiveness of heating or cooling.

A phenomenon known as ‘Short-circuiting’ can also reduce the effectiveness of ‘natural’ ventilation through fixed vents. This occurs when fresh air flowing in through fixed vents is not able to flow throughout the entire home. Long hallways, closed doors and other barriers limit the flow and mixing of air. Also much of the fresh air entering the home can often leave through another vent before thoroughly mixing with the indoor air. The result is ‘dead spots’ where air is stagnant or exchanged less often.

Another disadvantage of the fixed vents system is the uncontrolled entering of pollen, and traffic pollution into the indoor environment together with the fresh air.

The above problems can only be solved by creating a well sealed building envelope and introducing a balanced mechanical ventilation system. This will give the occupant full control over indoor air quality, relative humidity and comfort levels in the home.

Outdoor Relative Humidity (RH) levels – Sydney & Melbourne – 1996

Sydney			Melbourne
Month	Max	Min	Max	Min
January	69	61	60	44
February	73	64	64	46
March	72	62	67	47
April	71	57	72	51
May	72	55	78	58
June	74	57	80	63
July	69	50	79	61
August	66	50	74	57
September	62	51	68	52
October	61	56	63	50
November	62	57	62	48
December	65	59	60	45

These levels are monthly averages. Readings are taken at 9 am and 3 pm. Statistics on February 3, 1997, For long-term data for any location in Australia see the Bureau of Meteorology

Note – most months register in both cities at a level that is above the optimum (healthy) zone of 30% to 55% RH.

If you suspect unhealthy conditions in your home due to excessive humidity, then there is a tool known as a Thermo-Hygrometer to find out what is going on. This handy and healthy tool registers (digitally) indoor and outdoor temperature and indoor relative humidity levels. It memorises the minimum and maximum temperature and relative humidity readings as well as providing a read out of present conditions. Using a Thermo-Hygrometer is the best way to learn about and understand your indoor environment.

Sources:
* Canadian Home Builders Association, Building Manual, section 2: Aspects of Building Science.
* Residential Indoor Air Quality & Energy Efficiency. Peter du Pont & John Morrill,
American Council for Energy Efficient Economy
* Australian Bureau of Meteorology

What are the main sources of humidity in our homes?

The volume of humidity in the air produced by various household tasks
Activity (for a family of 4)	Litres/Week
Cooking (3 meals a day for one week)	6.3
Dishwashing (3 times a day for one week)	3.2
Bathing (0.2 litres per shower) (0.05 litre per bath)	2.4
Washing (per week)	1.8
Drying clothes indoors or use of a dryer without an external vent (per week)	10.0
Floor cleaning 30.5 m2	1.3
Occupants normal breathing and perspiration	38.0
The total volume of humidity per week	63.0 Litres

What are the key steps to improving Indoor Air Quality?

There are 3 key elements to solving indoor pollution problems and creating a healthy indoor environment in the long-term. They are:

Elimination

The first step to a healthier home is to eliminate offending chemicals from the indoor environment. This can be as simple as removing old paint pots, cleaning chemicals, etc from under the sink. When dust mites are a problem, eliminating products such as carpets and curtains can be of great benefit. Using paints that do not contain any VOC’s (such as the Dulux Breath Easy paint) is definitely a major step in the right direction.

Separation

If products can not be eliminated from the house for whatever reason, it will be necessary to separate them from the inside environment and our airways. This way, the chemicals, and their off-gassing cannot reach our lungs and therefore pose little risk to our health. An example of separation is the complete laminating of the kitchen cupboards, doors and benchtops. By laminating all sides, the formaldehyde, present in the medium density fibreboard (MDF), will be trapped and will not be released into the environment.

Another example
is the use of fibreglass insulation batts. The ADA technique (Airtight Drywall Approach) ensures that any fibres stay where they belong: behind the plasterboard. This technique is well practised in North America and Europe.Ventilation

Although natural ventilation ( opening windows, external doors or wall registers) has it’s benefits, the biggest drawback is the lack of control for the homeowner. Air will flow in and out of the house at will, depending on the whim of Mother Nature. When there is no wind, there is no ventilation. Another drawback is the loss of energy. To guarantee a supply of fresh air throughout the house, a balanced, ducted mechanical ventilation system is required. The Energy Recovery Ventilator is one such system . It introduces fresh, filtered air from the outside and at the same time, removes polluted, moist air from the house. During this air exchange, it also recovers over 70 % of the energy (heat or cool) that would normally be lost in the outgoing stale air and controls the humidity level in the house. The benefits of controlled humidity are: limiting dustmite growth, elimination of moulds and mildews and prevention of chemical off-gassing.

Why build a “Healthy House”?

Australians spend at least 90% of their time indoors. As our energy-conscious homes and office buildings are being built more tightly and with better insulation, indoor air quality and proper ventilation have become important health issues. In some instances, the air we breathe, indoors,may be more polluted than the outdoor air ! A ‘Healthy Building’ is designed not only to improve the indoor air quality, but improve the building’s energy efficiency.

What does it take to make a house ‘Healthy’ ?

A Healthy House is all about choices. People with asthma and allergies might be particularly interested in pursuing many of the technologies that make up a ‘Healthy House’. Others may want to take just a few steps, such as eliminating carpets, choosing household products more carefully, or controlling humidity to prevent dustmites.

Are there any design restrictions?

Building a ‘Healthy House’ is not restricted by house design. Some issues to be conisdered in building a ‘healthy house’ are:

Avoid the use of any building products that could cause health problems to the occupants,
Examine ways to eliminate certain pollutants by separating them from the indoor environment,
Recommend the use of certain building products and building technologies that will improve the indoor air quality of the home,
Introduction of a proper mechanical balanced ventilation system – Critical areas in the house such as the kitchen, bathrooms and laundry can create substantial pollution and high humidity levels, which need to be eliminated by means of ventilation, and
Insulating and sealing a house off properly is all part of the ‘Healthy House’ concept and will not only result in a more comfortable living space, but also reduced running costs.

What are the design principles for a “Healthy House”?

A ‘Healthy Building’ is one which is highly energy efficient, environmentally sound and addresses the health of the building’s occupants. This is accomplished through the introduction of a range of techniques and technologies which combine to protect the quality of the indoor air stream. There are four basic principles which need to be taken into consideration in order to make your home ‘Healthy’.

These Four Principles are:

Sustainable and Energy Efficient Building Design:The choice of building products is done in accordance with sustainable ideals. Timber and other building products are chosen which are either from a sustainable source and/or are low in embodied energy in their manufacture. A highly energy efficient design is needed in order to achieve an acceptable level of control over the indoor environment. This benefits our natural environment and our health through reduced energy consumption and increased indoor temperature control.
Elimination: eliminate (choose a ‘friendlier alternative) or significantly reduce the introduction of products which may prove to be toxic to the environment and unhealthy for you and your family; eg. medium density fibreboard (MDF) which contains high levels of formaldehyde.
Separation: If potentially unhealthy building products must be used within the building, separation techniques can be applied to separate it from the environment; eg. Formaldehyde containing particle board (MDF) can be sealed with laminate or paint.
Ventilation: Proper ventilation is crucial in order to reduce the build-up of pollutants and moisture within a building and to provide ‘fresh’ air for the occupants. Asthma and allergy groups around the world state that ventilation of a home is needed to control the level of dustmite and moulds; two key asthma and allergy triggers. The American Lung Association advocates mechanical ventilation of homes to control these two asthma triggers and provide a healthy level of indoor air for the occupants.

What is “Sick Building Syndrome”?

Sick Building Syndrome – US EPA Fact sheet Indoor Air Facts No. 4

The term “sick building syndrome” is used to describe situations in which building occupants experience acute health and comfort effects that appear to be linked to time spent in a building, but no specific illness or cause can be identified…. Solutions to sick building syndrome usually include combinations of the following:

Pollutant source removal or modification,
Increasing ventilation rates,
Air cleaning, and
Education and communication.

Does filtration improve indoor air quality?

The use of ventilation to improve indoor air quality is the main approach taken for reducing the harmful effects of airborne pollutants that enter the home or are generated internally within the home.

Ventilation helps to remove and dilute airborne pollutants within the home but may actually increase such pollutants depending on external local environmental conditions.

Filtration can be used in conjunction with ventilation systems to further reduce airborne pollutants and thereby improve indoor air quality. Effective filtration relies on:

a filter that removes airborne pollutants such as particles and gaseous pollutants,
an appropriate rate of air flow through the filter, and
a ventilation system to ensure adequate air exchange throughout the home.

Filters are rated to ASHRAE Standard 52-76 American Society of Heating, Refrigerating, and Air Conditioning Engineers. However, the efficiency of such filters is influenced by the rate of air that flows through them. Testing in-duct systems for “medium efficiency” has been undertaken by the U.S. Environmental Protection Agency and the results are shown below.

Filter Applications for In-duct Systems Based on ASHRAE Atmospheric Dust Spot Test
Air Cleaner Efficiency Ratings
10%	20%	40%	60%	80%	90%
Used in window air conditioners and heating systems Useful on lint. Somewhat useful on ragweed pollen. Not very useful on smoke and staining particles.	Used in air conditioners, domestic heating, and central air systems. Fairly useful on ragweed pollen. Not very useful on smoke and staining particles.	Used in heating and air conditioning systems, and as pre-filters to high efficiency cleaners. Useful on finer airborne dust and pollen. Reduce smudge and stain materially. Slightly useful on non-tobacco smoke particles. Not very useful on tobacco smoke particles.	Use same as 40%, but better protection. Useful on all pollens, the majority of particles causing smudge and stain, and coal and oil smoke particles. Partially useful on tobacco smoke particles.	Generally used in hospitals and controlled areas. Very useful on particles causing smudge and stain, and coal and oil smoke particles. Quite useful on tobacco smoke particles.	Use same as 80%, but better protection. Excellent protection against all smoke particles.
1. Efficiency rating by ASHRAE Standard 52-76 atmospheric dust spot test. Source: U.S. Environmental Protection Agency

Are Energy Efficient Houses Healthy?

The answer is yes they can be, provided the design of the house includes adequate ventilation with filtration. The main method currently used to significantly reduce energy loss from a building is to ensure that the building envelope (ie the building shell) is as air tight as possible. As a result, natural ventilation into the building is reduced and the issue of indoor air quality becomes a significant one.

In February 2005 the California Air Resources Board produced a draft Report on Indoor Air Pollution in California * which recommended to “Amend the building codes to address indoor air quality, with a focus on assuring adequate ventilation under all circumstances.”

The report also states that: ” California adults spend an average of 87 percent of their time indoors, and children under 12 years of age spend about 86 percent of their time indoors. …. the trapping effect of buildings, and people’s proximity to indoor sources of emissions, there is a much higher likelihood that people will be exposed to indoor pollutants than outdoor pollutants. Investigators have calculated that pollutants emitted indoors have a 1000-fold greater chance of being inhaled than do those emitted outdoors”

“Build Tight Ventilate Right”

In April 2006 the United Kingdom amended their building regulations to ensure that adequate ventilation is achieved in all new buildings. The UK building codes now state that:

“Ventilation is required for one or more of the following purposes:

provision of outside air for breathing;
dilution and removal of airborne pollutants, including odours;
control of excess humidity (arising from water vapour in the indoor air); and
provision of air for fuel-burning appliances.” **

The four approved methods of achieving such ventilation are as follows:

Background ventilators and intermittent extract fans;
Passive stack ventilation;
Continuous mechanical extract; and
Continuous mechanical supply and extract with heat recovery.

Heat Recovery Systems can provide fresh filtered air to buildings as well as recovering up to 80% of the heat from the exhaust air, thus maintaining energy efficiency as well as providing acceptable levels of indoor air quality.

Read the draft Report on Indoor Air Pollution in California * pub. February 2005.
Download document Part F “Ventilation” – United Kingdom** pub. 15 March 2006.

What is HRV technology?

HRV stands for Heat Recovery Ventilator. It is a technology that has been used for the last 40 years worldwide to provide high quality indoor air into buildings for the benefits of the occupants. HRV technology is used for commercial and industrial buildings as well as residential buildings.

A genuine HRV system will provide the following:

fresh air into a building,
extract stale air from the building,
filter the fresh air entering the building to remove pollutants,
recover heating and cooling from the stale air using a heat exchange core,
and transfer the recovered heating or cooling to the incoming fresh air.

In housing, HRV systems are fully ducted systems delivering fresh filtered air from outside the building (external to the building and associated roof space) to the living and bedrooms and extracting stale air from high moisture areas such as bathrooms, kitchens and laundries. Typically, an HRV is able to recover 70 to 80 percent of the heat from the exhaust air and transfer it, via a heat exchanger, to the incoming air.

This type of ventilation is referred to as balanced mechanical ventilation.

Whole building ventilation

What is it?

It is a ventilation machine that is specifically made for new buildings or ‘renovated’* old buildings.
It filters the outside air as it comes in and removes old (or polluted) air from inside the building.
The INCOMING and the OUTGOING air come in and out at the same rate (so its called a balanced system).

Its purpose?

It provides the whole building with a continuous (and controlled) fresh airflow, no matter what is happening in the building or outside.
When we say ‘controlled’ it means we have a say in how much outside air is brought in and how filtered that air is.

What else does it do and why is it now so important?

Depending on the season we may have a ‘heater’ or a ‘cooler’ on inside the building (lets call this ‘heat’ or ‘cool’ energy). It costs money to heat or cool our homes.
The ventilation machine brings new air in and removes the stale old air, it does not heat or cool the air.
The air in your home has been either been heated or cooled by a heater or air conditioner. As the air leaves the building the ventilator (AIR2ENERGY systems) catches the energy (hot or cool) and passes it to the new air stream coming in. This is an energy (heat or cool) transfer.
The air streams never mix but pass so close to each other that the energy (heat or cool) flows to the new air.

So, that means that we don’t lose that energy to the outside. We have paid to heat or cool our inside air and by recovering that and reusing it, we become very energy efficient and also save money.

Two types with different names for different jobs.

One is called a ‘Heat Recovery Ventilator’ (HRV) because it was invented for cold climates to ‘catch’ the heat in the old or polluted air that is being removed.

So not to waste that ‘heat’ the ventilator passes that ‘heat’ (or energy) to the new air being brought in.
This saves an enormous amount of energy (heat) being lost outside as well as new energy being used to reheat the new air coming in. HRVs can also remove excess moisture from your home.

A variation of an HRV is an ERV (or Energy Recovery Ventilator).

Like the HRV, the ERV allows you to ‘recover’ heat or cool but also to monitor and control moisture in the air to suit the climate. They are usually used in hot humid or hot dry climates. The moisture comes from what we do in the house. We breathe, our bodies give off moisture, we cook and shower etc. This moisture affects your health and the health of the building.
The created moisture is absorbed into our furnishings and then released. When released the ‘moisture filled’ air is full of pollutants from the glues and chemicals used in the construction process. These pollutants cause health problems- asthma and allergies. Mould and spores love moisture too. Building structures are also badly affected by moisture.

Why do buildings, people and the planet need it NOW?

It’s all about the air quality in the building. We try to reduce heating and cooling costs by building structures that are well insulated and don’t leak air.
These ‘tight’ buildings don’t allow ‘moisture filled’ air to escape thereby creating potential health problems.
CO2 is one of the offending gases warming the planet. If we reduce our energy requirements for heating and cooling then we help reduce C02 levels.
Reducing air pollution is crucial.

*a ‘renovated’ building will have all existing gaps and cracks sealed to reduce air leakage.

Balanced Ventilation systems – The key to energy efficiency?

When building a new house the issue regarding ventilation is one that must be addressed! With the increasing demand for energy efficient buildings, the end result of the design and building process are often buildings that have significantly reduced air leakage. This is the desired result of energy efficient design and construction, as reduced air leakage means reduced energy loss and therefore reduced energy consumption for heating and cooling. ie fewer gaps and cracks means less energy loss from the building. However we need adequate ventilation for all of the following purposes:

provision of outside air for breathing;
dilution and removal of airborne pollutants, including odours;
control of excess humidity (arising from water vapour in the indoor air); and
provision of air for fuel burning appliances.

Ventilation systems can place undue negative or positive pressure on a building and cause extra loss of energy through increased air leakage. With new buildings; kitchen range-hoods, gas fired heaters and bathroom, ensuite, toilet exhausts may not function correctly, if at all, due to the “tightness” of the building. As well depending on climate, moisture can be driven into the wall materials and cause mould as well as structural damage.

Build Tight – Ventilate Right

We need buildings that have minimal or no air leakage for maximum energy efficiency but we also need adequate ventilation for the above reasons. A balanced ventilation system solves this problem by ensuring the same amount of air enters the building as is exhausted from the building. When coupled with heat or energy recovery a balanced system contributes to the best solution for achieving the most energy efficient building. The German Passive House (Passivhaus) standard incorporates balanced mechanical ventilation with heat recovery to achieve the most energy efficient buildings in the world.

Existing buildings can be tested for air leakage, retrofitted with a range of energy efficient products and installed with a balanced ventilation system with heat recovery to achieve very high energy efficiency. Again the German Government Energy Agency DENA has demonstrated this with refurbishments of over 375 buildings resulting in a reduction of the energy consumption to a level well below that of a comparable new building.

Read a report Efficient Homes – German Experiences with Deep Retrofit on the project from the The Insitute of International and European Affairs Retrofit Conference 2011

Measuring Building Performance – how do we test for air tightness?

For either new or existing buildings a detailed and accurate measurement of air leakage is important to fully understand the energy performance of that building. Up to 20% of a building’s heating and cooling can be lost by uncontrolled air leakage of the building envelope. New, highly energy efficient residential buildings should have a natural air leakage rate of no greater than 10 air changes per hour at 50 Pa. Internationally, the accepted range for energy efficient housing is between 0.3 and 0.5 ach @50Pa.

By using a blower door device we can identify the overall leakage area of the building. Blower door technology is used in many countries, where energy efficiency is mandated, to measure the airtightness of building envelopes, diagnose and demonstrate air leakage problems, estimate natural infiltration rates, estimate energy efficiency losses from building air leakage, and certify construction integrity. A Blower Door consists of a large fan which is mounted in a frame. The frame is placed in an exterior door and used to either depressurize or pressurize the house. Once the problems have been identified these can be addressed and as a result the energy performance of the building can be maximized.

Read the report: Low Energy Buildings In Europe: Current State of Play, Definitions and Best Practice	Pub.	Sept. 2009.
Read the review: Steering through the maze -Nearly zero energy buildings: achieving the EU 2020 target.	Pub.	Feb. 2011.
Read the paper: User Evaluations of Energy Efficient Buildings	Pub.	Feb. 2011.

Enclosure Air Tightness Testing Volume vs Surface Area Targets ACH vs PERM

Enclosure Air tightness testing Volume vs Surface Area Targets (ACH@50 vs Permeability rate)

Airtightness on large enclosures can get tricky and complicated. We see some pretty questionable things in specifications for the testing of these types of facilities, which in most circumstances are pretty airtight considering the type of construction that they are but the metric they are measuring to makes no sense what so ever.

Targeting ACH is NQR (Not Quite Right)

For example, using ACH@50Pa(Volume) or ACH@Ambient-4Pa(Volume) instead of a permeability rate(Surface area) to understand how leaky a commercial/industrial facility/Oil Rig refuge actually is, means that the larger the enclosure, the more airtight it is. So a uniform standard leakage rate cannot be specified in this specification. As an example. Compare the ACH for these 3 examples.

A standard single story house

Floor Area: 125m2

Volume: 300m3

Surface area: 389.5m2

A building at 5 m3/h/m2@50Pa would be 6.5ACH@50Pa

A standard single story Passive house

Floor Area: 125m2

Volume: 300m3

Surface area: 389.5m2

A building that achieves passive house .6ACH@50Pa needs to achieve .462 m3/h/m2@50Pa

Smaller volumes or components of buildings trying to achieve .6ACH@50Pa can be next to IMPOSSIBLE to achieve when services penetrations and windows are a part of the building fabric.

Not so much of a problem, the permeability rate and Air change rate are very similar, due to these types of buildings usually being quite small. Volume and Surface area numbers are largely similar. (However, McMansions or Large homes, can enjoy the benefits of ACH)

Small Commercial Building

Volume: 20m x 20m x 12m = 4800m3

Surface area: 1760m2

A building at 5 m3/h/m2@50Pa would be 1.83 ACH@50Pa

Identical Build quality as the home but it enjoys over THREE times lower ACH Rate

Large Commercial Building

20m x 20m x 260m = 104,000m3

Surface area: 21600m2

A building at 5 m3/h/m2@50Pa would be 1.03ACH@50Pa

Identical Build quality as the home but it enjoys a FIVE times lower ACH Rate. This building could be Passive house air tight if passive house didn’t have the rule that buildings larger than 4000m3 in volume need to use a permeability rate.

Using ACH on Commercial buildings, Oil & Gas rig refuges or any type of large enclosure larger than 3000m3 in volume, means the larger the enclosure, the easier it is to pass a particular target inadvertently. For build quality, a permeability rate which uses the surface area of the building, requires a target based on air flow through a square meter of building envelope with simulated airspeeds of 32km/h winds. That way it is a standard number for all facilities of that type, and the build quality can then actually be compared meaningfully and reproducibly no matter the dimensions and volume of the building.

Busting the myth on solar thermal reflective paints, and having a cool roof.

Some Information on Ceramic Solar Thermal Reflective Paints and Having a Cool Roof.

Here at Efficiency Matrix, we are not rocket scientists, but some of the claims/assumptions on the internet need to be straightened out and explained so that most people can understand cool roofs and advertised Ceramic Solar Thermal Reflective Paints. There are alot of claims from some paint suppliers and we break it down here. NeoTech Coatings has disputed the facts inside this page, however they do NOT wish to outright prove their ceramic paint is better than a standard white paint outright.

First, Let’s explain the building envelope: It includes the external walls, ceiling, and floor that separate you from the outside environment.

Considering that reflective paint works by deflecting radiant visual energy, we decided to model radiant energy transfer comparisons using different building envelope products.

Before we go into modelling what white paint and solar thermal ceramic reflective paints can do, let’s talk about the different spectrums of energy from the sun and the spectrum of energy from building materials and materials that the earth is made of.

When considering different building envelope products, it’s important to understand that energy radiates from all objects; the sun radiates energy primarily on the visual spectrum and near-infrared, and Indoor objects in a house here on Earth radiate on the middle to far-infrared spectrum.

Three methods of energy transfer affect energy efficiency in the building envelope.

Conduction: which is countered using an insulation R-value
Convection: which is countered with an airtightness layer
Radiation is countered with a radiant barrier, e.g., Low-E films, shiny metallic surfaces and white paints, with additives claiming better near-infrared deflection performance. This is called the albedo effect. Insulation with an R-value can also block this form of energy transfer because this type of energy is transferred into the building envelope via conduction.

As a silver bullet argument, a paint/coating 1 mm thick does not provide any meaningful insulation. As an example to justify this claim, the best insulation in the world (aerogel, k=0.02, so R=t/k=0.001/0.02=R 0.05 m².K/W) has an R-value of .05, where most homes in Australia require ceiling insulation of R 4.1.

High solar reflectance (white paint) reduces direct sun energy absorption (albedo); hence, a cool roof energy-saving claim is supported. The chart above shows how much energy makes the earth’s surface in the visual spectrum range. It’s huge! But it only benefits energy efficiency for a few hours of the day. The sun only actively forces its energy on our buildings during 3-4 peak hours, yet we expect comfort 24 hours a day.

Earth receives energy from the sun through solar radiation—radiation with varying wavelengths along the electromagnetic spectrum. The sun emits strongly in the visible light range, producing ultraviolet and near-infrared radiation. This spectrum is highly dependent on the effect of the atmosphere. The earth radiates heat back to space mostly at much longer wavelengths (Middle to far Infrared at a much lower intensity).

Moving onto the myths that are doing the rounds regarding the benefits of NASA Technology ceramic highly-reflective/white paint. At the bottom of this article, we modelled different solutions for keeping heat out of a building and keeping heat inside of the building, using different building envelope materials.

Myth #1

Solar reflective paint/coatings can be applied to the inside of a building to keep it warm.

White Paint and Ceramic Solar Reflective Coatings are only effective in reflecting/rejecting sunlight or energy from the sun. Taking away the sunlight provides no building performance benefit.

An Australian company pursued this marketing strategy, costing them $ 400000.

https://www.accc.gov.au/media-release/dulux-to-pay-400000-for-misleading-cooling-paint-claims

Other court cases have also arisen from special reflective paint claims in the US.

Kryton Coatings International, Inc., et al. – Complaint (ftc.gov)

More recently, there is this one. Year: 2020

Superior Products International II, Inc. | Federal Trade Commission (ftc.gov)

An excerpt from one of the court case proceedings regarding a cooler roof painted with ceramic paint vs white paint.

https://www.ftc.gov/system/files/ftc_gov/pdf/2022-09-22%20-Memorandum-and-Order.pdf

Sarking performs far better than any paint due to its high-reflective capabilities in the medium to far Infrared spectrum, which all homes radiate internally.

To put this into perspective, sarking (reflective foil) does NOT perform nearly as well as bulk insulation in keeping energy inside a building envelope, so how could a visually coloured thin layer of paint compare to sarking? Introducing a thin layer of paint will NOT insulate the building envelope. The only example of where painting the inside of your house with thermal reflective paint might be of any use is if you plan on launching rockets into earth orbit from inside your living room. Which is what NASA originally used the thermal reflective paint for.

It could explain why they demonstrated the use of a blow torch in this video to test how “insulative” their product is on TV. In other videos online, testing of these paint products with infrared heat lamps can be found, but unfortunately, such high-intensity near-infrared heat does not radiate from everywhere inside the building envelope other than the actual heater itself. On top of that, he seems to be holding the blow torch further away from the tainted paint.

Myth #2

The other related Myth, which is also spoken about,

Painting your roof with a solar reflective paint can assist the performance of a building in winter and cold nights

Solar reflective paint does not keep your house warmer in winter because it is solar VISIBLE reflective, not infrared reflective. Thus, a house warmed by its heating system in winter loses some heat through the roof by infrared radiation to the night sky, and it is not blocked by solar reflective paint.

Myth #3

Urban Heat Island effect is not considered in the modelling simulations, which is critical for showing cool roof benefits, when mechanical plants are air cooled and roof mounted.

The heat island effect is only significant when there is no wind (i.e. local high energy density in cities), but almost always (in Melbourne, Australia specifically), at peak loads, there are hot northerly winds, and this disrupts the heat island effect, thus heat island effect on rooftop equipment performance is nullified. Other cities may be less windy, and Urban Heat Island may come into play, but it is not likely.

Sarking Effectiveness is no Myth.

Sarking can reflect and keep a home warm, but can also keep a building cool in warm climates.

It most definitely helps, but…

Dust and mould buildup on its surface over time can significantly degrade its performance. Foil-building wraps need to remain shiny and clean for them to perform optimally. This happens naturally with vertical foil in walls and foil facing down, which remain dust-free for 50+ years, hence providing reliable reflective insulation. However, foil facing upwards degrades from dust deposition, and the Australian Standard 4859 describes this degradation in its performance.

Some products are coming to the market now where there are layers of foil with an appropriate gap in between. These types of products can produce some great results.

Because these materials are non-vapour permeable in colder climates, they can cause moisture issues in wall systems, contributing to mould growth.

The internal cavities of walls/ceilings and subfloor

The internal cavities of the building envelope, whether walls, subfloor, or roof area, can be problematic areas for condensation, leading to unhealthy mould and material damage. It is very important the insulation and vapour barriers are designed to avoid condensation.

There are many potential solutions for stopping heat transfer from extremely hot and cold days, and it is best to seek an expert for the optimum cost-effective solution for your building. For example, solar reflective coatings/white paints have great benefits in hot, sunny locations, and if the roof has poor insulation, they are less cost-effective if the roof is already well insulated. Often, the most cost-effective retrofit is sealing a roof with spray foam insulation, as this can also reduce thermal bridging at the structural frame that are significant thermal bridges.

What the modelling says

We modelled the following insulation/energy deflection building products and systems.

- Solar reflective coating paint

- White Paint-[White 16] (Performance Data Adopted from Alucobond)

- Black Paint (Performance Data Adopted from Alucobond)

- Brushed aluminium Roofing (Performance Data Adopted from Alucobond)

- Sarking/Foil Paper

R-4 Bulk Insulation This modelling only looks at radiant temperature/energy from the sun’s full solar spectrum coming onto objects that make up the building envelope.

Real solutions for improving the performance of a roof.

If a building does NOT have insulation, using a standard off-the-shelf white paint (White 16) or a ceramic solar reflective paint CAN improve comfort within a building during a hot summer day but not in cold winter climates (Solar Reflective Coatings may or may not slightly outperform standard white paint). If there is no insulation in your building, consider installing conventional insulation.

If there is insulation, consider the below retrofits.

Repairing sarking/foil that is torn and ripped under a tin roof with foil tape.
Fix up gaps in the insulation on your ceiling.
Apply normal, durable, good-quality outdoor WHITE or light-coloured paint from your local hardware store or paint distributor. The cost of Ceramic material paints should be considered before committing to these products.

Understand that real energy efficiency performance is realised by improving airtightness and ensuring that insulation is abutted consistently to this air barrier throughout the building envelope. A solar reflective coating does not meaningfully improve energy efficiency over a simple white (white 16) coloured paint if your ceiling is consistently insulated and airtight. And even if the ceiling isn’t consistently insulated, the roof area temperature is not lowered enough using solar reflective paint to make a quantifiable difference over plain white paint.

Some of these Solar Thermal paint products may offer better durability for longevity over standard white paint, which may add significant value to an asset.

References

An ‘Insulating’ Paint Salesman Is Tripped Up By His Own Product – GreenBuildingAdvisor

https://www.enn.com/articles/32849–a-low-emissivity-coating-that-really-works

http://www.treehugger.com/green-architecture/ceramic-paint-on-insulation-does-it-work.html

Some research papers:

https://nrcawebstorage.blob.core.windows.net/files/staticcontent/masterpages/technical/symposium/pdf/04_brehob_paper.pdf

https://energy-seal.com/wp-content/uploads/Department-of-Energy-study-on-Ceramic-vs-non-ceramic-roof-coatings.pdf

A video by Melbourne University discusses the benefits of a simple light (White is the best) colour as opposed to a dark colour for roofs. Mainly beneficial for uninsulated roofs during summer ONLY. eg Heritage or Storage Sheds.

Visions: Cool Roofs – YouTube

by Joseph Cheung & John Konstantakopoulos

Another more recent video on the performance of white paints, while also adding a ceramic additive too.