A healthy home - Nauticool · Tropical climates has extremely hot and humid summers. Hence, homes in this areas require maximum shading, ventilation and heat release to moderate the

THE IMPORTANCE OF THE IMPORTANCE OF THE IMPORTANCE OF THE IMPORTANCE OF VENTIVENTIVENTIVENTILATIONLATIONLATIONLATION

OUTLINE A healthy home Why is ventilation important? Heat flow How ventilation works Air changes per hour

What you need to know before planning a ventilation system Ventilation and air conditioning Types of ventilation Energy efficient ventilation BCA ventilation requirements Sick building syndrome Solar powered fans Case study

A healthy home The air quality inside our home has an impact to our health conditions. Poor quality indoor air can cause a range of adverse effects to our health from mild and generally non-specific symptoms like headaches, tiredness or lethargy to more severe effects like aggravation of asthma and allergic response (Cook, J., 2002). The degree of ventilation available in the home plays a very important part of removing the air pollutants and keeping the indoor environment healthy. Proper design and orientation allow breezes to enter the home and through convection currents, draw stale air out and fresher air in. The problem with artificial cooling systems is they do not introduce fresh air. The ducted air systems for example, according to “A guide to indoor air quality in the home for buyers, builders and renovators”, heat or cool recirculated indoor air but don’t introduce fresh air from outdoors or attempt to remove pollutants. Evaporative cooling systems, on the other hand, increase indoor humidity and may increase levels of mould or dust mites within the home.

Reardon & Clarke discussed (2010) that by incorporating passive design ideas to your home, efficiency of the building envelope will be achieved by minimizing the heat gain from the external environment and facilitating heat loss through air movement, cooling breezes, evaporation and earth coupling.

Effective ventilation is an important way to create a more comfortable and energy efficient home. It prevents the build up of heat, which can go as high as 70°C during the hotter months, in your roof space.

Tropical climates has extremely hot and humid summers. Hence, homes in this areas require maximum shading, ventilation and heat release to moderate the internal environment. A healthy home reduces hazards to human health by lowering the presence of toxins and promoting natural light and ventilation (Smart & Sustainable Homes).

Why is ventilation important?

As explained by Sustainability Victoria (2010) in its Passive Solar Design fact sheet, ventilation is the deliberate replacement of inside air with outside air to replenish the oxygen inside and remove moisture, odours, smoke, heat, and airborne bacteria, keeping indoor air healthy for the occupants. Natural-occuring air temperature and pressure differences can be applied or through mechanical means like exhaust fans. Furthermore, ventilation controls air movement and helps mimimise the need for supplementary heating and cooling around the house. This in turn minimise the energy costs and provide substanstial savings while improving the comfort level.

Heat flow

Heat from the sun enters a home in four ways:

1. Radiant heat transfer from roofing material to attic air, which in turn can re-radiate through the ceiling.

2. Entry of certain wavelengths of light through glass windows. 3. Radiant heat transfer from the building materials used for walls. 4. Hot air simply entering through open windows, doors, cracks etc.

According to Connection Online, once heat enters your home, it can be slow to dissipate if there's no way for air to escape. Even with evening temperatures dropping by 10ºC below the temperature inside a house, it can take ages for the house to cool. If the temperature inside remains high during the evening, the house will quickly heat up the next day too.

How ventilation works Planning Services Special Projects Unit discussed that poorly ventilated roof-spaces get incredibly hot and can reach up to 70°C. When the sun hits the roof it transfers heat down and superheats the trapped air in the roofspace. This heat is then transferred down through the ceiling into the room below. NABERS discussed ventilating the roof keeps a home cool. It greatly reduces the amount of accumulated heat, which eventually works its way into the main part of your house. Ventilated roofs are about 16°C cooler than unventilated roofs. Properly sized and placed louvres and roof vents help prevent moisture build-up and overheating in your attic. Ventilation is particularly important for the purpose of cooling. Based on the article “Why is ventilation important?”, the best ventilation systems work by taking warm air out of the home between 6pm and 3am, and replacing it with cooler air. This is called an ‘air change’. As the temperature heats up outside during the day, you then lock up your house to stop heat from coming in. This can be achieved by shading using awnings, curtains, blinds or other mechanisms. When the air moves faster than the speed of natural air leakage, ventilation has a cooling effect on the human body. At air speeds of 0.5-1.0m per second, the body will feel 2-3° cooler in 25°C air (Sustainability Victoria, 2010). The Passive Solar Design fact sheet further discusses that openable windows, doors and the interior layout offers good ventilation by taking advantage of the natural breezes and convection flow. Fans can be used where natural ventilation is inadequate, or where the rapid removal of air contaminants is required.

Air changes per hour According to the Air Movement fact sheet, a typical home with a wall vent in each room will have approximately one air change per hour (one air change per hour occurs when the volume of inside air is replaced totally by outside air in a period of an hour). Sealing the

vents reduces the air change rate to 0.5 per hour, which reduces overall energy requirements by up to 15% and still allows for adequate ventilation.

As discussed in Build.com, the number of air changes you need per hour depends on the volume, position and surroundings of your home. The amount you can achieve depends on the flow rate of your ventilators. In a typical brick-veneer home that features eaves and has trees near the windows, around two to three air changes per hour should be enough. This can usually be achieved with four or five wind-driven whirlybird ventilators, or two powered ventilators, which can move up to 2,400 cubic metres of air an hour.

In an older style home with no eaves or trees, you may need up to five changes an hour. The higher the ventilation rate, the better the conditions. But there is a limit. After a certain point, regardless of how much money you spend, there is an optimal level of ventilation for every home. This is determined by the volume of air in the home, shading, trees, and insulation.

What you need to know before planning a ventilation

system Before you plan a ventilation system for your home, you need to know the volume of air in your home and compare that to the capacity of a ventilator. That is, you need to ask how many cubic metres of air needs to be moved each hour, and what sort of mechanisms will allow two to three air changes an hour in your home.

These are the vital calculations. Keep in mind though that when it comes to ventilation it really is a case of getting what you pay for. Whirlybird vents, for example, can be bought for around $50, but you shouldn’t expect to get 'air conditioning' type results from them. It just doesn’t happen. Some newer hybrid ventilation systems can move up to 2,400 cubic metres of air per hour while only consuming 40W of power. This, however, can easily cost a couple of thousand dollars. The trick is to find a cost-effective balance - and one that will work in harmony with any other heating and cooling measures you've got in place.

If you're considering building a passively heated or cooled house, ventilation's a tricky concern because of the fact that your house will be more or less airtight. In many cases this will require some carefully planned mechanical ventilation (such as an energy recovery ventilator).

Ventilation and air conditioning

Air conditioning in general is a far better manager of climate control than ventilation. However, if you team the two together, controlled ventilation (teamed with good insulation) can vastly improve the operational efficiency of air conditioners. Properly planned ventilation is particularly useful for ducted systems, as it can lower the temperature in ceiling cavities by up to 10°C, thus reducing the heat load on the ducts.

Without air conditioning, a ventilation system in partnership with good insulation can reduce your home’s temperature by as much as 9 to 10°C. While this may not be good enough in the most extreme climates, it could easily prove adequate if your home employs good passive design techniques, and mechanical cooling is only necessary for a few days of the year at the most. According to Australian Building Codes Board 2010, utilizing ventilation purge warm air from the building when outside temperatures are lower (usually overnight) can also reduce the need for air-conditioning. A reduction in the need for air-conditioning means less energy consumption and a subsequent reduction in greenhouse gas emissions.

Types of ventilation

The type of ventilation system you choose can have a dramatic effect on the quality of cooling you get in your home. Powered options may be more effective, but they will cost you more. Natural ventilation will cost you less, but relies on nature to work. Hybrid systems, however, may offer you the best of both worlds. There are three main types of ventilation in a passive solar designed home, as discussed by Sustainability Victoria (2010):

• Cross-ventilation – that used differential wind pressure through proper placement of windows and doors.

• Exhaust fans – use small amount of electricity. Exhaust fans like those installed on ceiling and roof-mounted can extract warm air, creating a pressure imbalance that will draw cool air from outside via open windows or doors to replace the warm air inside. Powerful whole house fans move large volumes of air quickly. It use moving air to create naturally cooling

cross-ventilation in rooms, while removing hot air from the roof space. Energy usage is minimal for these kinds of fans.

• Ceiling fans – are economical and efficient way of creating cool breezes. It provides additional air movement in summer. Overhead fans circulate large volumes of air and encourage evaporative heat loss from the body.

Other types of ventilation systems include (Fitzgerald, 2011)

• Rangehoods – are mounted over the stovetop and vent to outside or filter the air before returning it to the room. These are used in the kitchen to vent away smells, grease, cooking odours, steam and the like.

• Solar ventilation – a relatively new concept that uses solar energy in the roof to operate a fan. The fan draws in fresh air and filters it, removing the contaminants, and delivers it into the home.

Energy efficient ventilation

Providing ventilation in the roof space removes the hot air to prevent heat accumulation that add extra heat to your home. Ideally home should have a minimum of two openings in each room to faciliate cross ventilation. Roof, eaves and floor vents can be installed to help to cool the home.

According to Adelaide City Council, when natural ventilation is inadequate or not provided, BCA requires that a room of a building should be ventilated with outside air using fan or other mechanical system that complies Australian Standard AS1668.2 - Mechanical ventilation for acceptable indoor-air quality.

Installing roof-mounted exhaust fans can extract hot air from the roof space at night and replace it with cool air. These can be activated by wind or operate on a thermostat (Sustainable Energy Authority Victoria). Fans can costs as little as 1c per hour to run and works well with the natural ventilation system. Choosing fans with longer blade options (1400mm) are more effective and can increase the home energy rating by one or two stars (Barrett, 2012). Compared it to air-conditioning that can cost around $180 per quarter, you can save a lot from your energy bill using fans.

The use of whole house fan can be used to force hot, stale air out of your roof space and replaces it with cooler air drawn in from the open windows and doors. It can remove up to 20 times the volume of air from your hot roof space compared to roof traditional roof ventilation systems like whirlybirds. Replacing the hot air from the roof space with cooler air, rather than just releasing some of the hot air, cools your home quicker and keeps it cooler longer (AirExchange). Passive roof ventilators or new solar roof ventilators can also be installed in homes They use no power, quiet, can move 14 times the volume of air than the old whirly bird ventilators and can very well reduce the heat in the roof space (Barrett, 2012).

BCA ventilation requirements

There are few building code requirements that you must be aware of when planning for a ventilation system in your home. As stated in Building Code of Australia (BCA) 2010 Volume Two for Class 1 and 10 dwellings, the objective of ventilation of a building is to safeguard occupants from illness or loss of amenity due to lack of air freshness. Hence, the space used by occupants in a building must be provided with means of ventilation with outdoor air, which will maintain adequate air quality. The mechanical air-handling systems installed must be able to control the circulation of bad odours and the accumulation of harmful air contaminants. BCA Table 3.12.4.1 provides the minimum total ventilation requirement opening area per habitable room, which means a room used for normal domestic activities that includes the bedroom, living room, lounge room, television room, kitchen, dining room, etc.

Note: Because evaporative coolers are less effective than ceiling fans in more humid locations, the requirement for ventilation opening in climate zones 1, 2 and 5 with an evaporative cooler is the same as without one.

Clause 3.12.4.2 requires that ventilation opening must comply with any one of the following: a. Ventilation opening in the room must be connected by a breeze path to

another ventilation opening in another room; or

b. The room must be provided with a minimum of two ventilation openings located with the same room.

In humid locations, such as Darwin and Cairns, evaporative coolers would not provide the same cooling effect as in dryer climates. Although they would provide some benefit from the air movement if operated in a “fan-only” mode, they would cause discomfort, possible condensation and possible mould growth if operated in an evaporative “water-on” mode. However, even though a concession is not given in climate zones 1, 2 and 5, there are locations, particularly in climate zone 5, where evaporative coolers would be effective (Building Code of Australia 2010 - Volume Two. Class 1 and 10 dwellings). This is a typical plan view example of cross flow ventilation in a house.

(Source: Australian Building Codes Board, 2010)

BCA 3.12.4.3 specifies the requirements in the use of ceiling fans and evaporative coolers, which are as follows:

• permanently installed; and

• have a speed controller; and

• for a ceiling fan, have a blade rotation diameter of not less than–

a. 900 mm for a space of not more than 15m2; and

b. 1200mm for a space of not more than 25m2.

The performance of the fan will depend on a number of factors including blade design, ceiling clearance, the proximity of walls and the power of the fan. The need for artificial cooling is reduced by maximising the cooling effects of natural cross flow ventilation and the use of ceiling fans or evaporative coolers. Ventilation, even by ceiling fans or evaporative coolers, is a cost effective solution results in lower greenhouse gas emissions than

refrigerated air-conditioning (Australian Building Codes Board 2010).

Sick building syndrome

Failure to comply with the building standards could result to what is known as “sick building syndrome”. In an article published in the Town of Cambridge website, the symptoms of sick building syndrome range from allergies, headache and fatigue to nervous-system disorders, cancer and death. Indoor pollutants that contributes to this include formaldehyde, volatile organic compounds (benzene and trichloroethylene or TCE), airborne biological pollutants, carbon monoxide and nitrogen oxides, pesticides and disinfectants (phenols) and radon. Studies have shown that people need fresh air and natural light for their health and well-being. Most of the time, sick buildings are created by inefficiencies with air conditioning and ventilation (Connection Online Pty Ltd.)

Solar powered fans Ventilation enables the roof space to renew the air compresed in the roof space transferring down through the ceiling and into the home (City of Subiaco). A cost efficient way to provide ventilation in the roof space is to install solar powered roof fans. Once installed, it cost nothing to operate and require no power, relying on solar energy. As discussed in the Home Improvement Pages, solar powered fan is any type of fan where the motor is powered by solar technologies. When sunlight hits a solar cell, it converts the sun’s rays into electricity and then powers the fan. Solar roof fan, also referred to as solar roof vent, draws hot air out of the attic and lower the temperature of the home. Because it runs on solar energy, it lets you save from the cooling energy costs and help reduce your home’s carbon emission. According to an online article published in Solar Energy for Homes, several brands of solar roof fans are available in the market with prices that can be as low as $30 or $40. However, the low priced model are not recommended because of poor construction and cheap materials. Higher quality models can be a bit pricey with prices ranging from $375 to $600. Some solar roof fan models like Solar Whiz removes heat directly from the interior of the building while preventing mould and mildew (Sydney Ventilation). Some like Sun Lizard creates heat when the sun shines and the solar fans spin pumping heat into a building during winter and pulling heat from a building in summer (Department of Science, Information Technology, Innovation and the Arts).

With the increasing electricity price, installing solar powered roof fan will help cut the household’s energy usage thus reducing the electricity bill. In 2011, Australian Energy Market Commission released an information sheet on Retail Electricity Price Forecasts. It states that between 2009-2010 and 2012-2013, most Australian states and territories face nominal increases of 20-40% in residential electricity prices. Carbon price, according to Clean Energy Future, is expected to add around 10% to househould electricity prices in 2012-2013. Hence, ventilating your roof space with solar roof fan doesn’t only maintains quality indoor air but lets you save from your energy costs. The graph below shows the composition of your electricity bill.

(Source: As published in Clean Energy Future - National average figures provided by the Commonwealth Treasury)

Depening on the features of the home, solar roof fans can provide annual savings from 5% to 40%, according to Solarvent.

Case study

A house in Clovelly, an innser coastal suburb of Sydney, turns site constraints into opportunities. Your Home Technical Manual features this award-winning Sydney renovation.

The renovation reduces the existing home’s environmental impact and incorporates innovative technologies as an integral part of the architectural expression. Installing solar powered fans was part of the renovation. The renovated house is designed to minimise the need for artificial heating, cooling and lighting and avoids reliance on mechanical systems like air conditioning in order to achieve ongoing cost savings and environmental benefits. A proprietary solar-powered heating and cooling system is used to enhance indoor comfort without creating any greenhouse gas emissions. The system is a recent Australian invention and consists of two solar-powered fans and a heat collector on the roof. The heat collector is a metal and glass box, similar in principle to a solar hot water panel. The system works by raising the ambient indoor temperature in winter and extracting hot air in summer. In winter the fans draw air from ceiling level, heat it to about 50º Celsius in the collector, and pump it back to floor level via insulated ducts. In summer the fans draw hot air from ceiling level out through an opening flap on the collector. For this home, one heat collector panel was installed as a trial, however in retrospect two panels would have been more appropriate. The cost of the system was approximately $2,500. Ceiling fans are also used to keep the home cool in summer. There is no air-conditioning or auxiliary heating used. The renovation was completed prior to the implementation of BASIX, however retrospective scoring using BASIX estimates the home uses 25 per cent less energy and 54 per cent less water than the average NSW home. (Source: Your Home Technical Manual)

Reference List Cook, J. (Ed) (2002). A guide to indoor air quality in the home for buyers, builders and renovators. Australian Government Department of Health and Ageing. Retrieved from http://www.health.gov.au/internet/main/publishing.nsf/content/B9252301BA2F6A4ECA2573CB0082ABD1/$File/healthyhomes.pdf Reardon, C., & Clarke, D., (2010). Passive Cooling. Your Home Technical Manual. Retrieved from http://www.yourhome.gov.au/technical/fs46.html

Smart & Sustainable Homes.. Designing for Queensland’s Climate. Queensland Government Department of Public Works. Retrieved from http://www.hpw.qld.gov.au/SiteCollectionDocuments/SmartDesignQldClimate.pdf Sustainability Victoria (2010). Passive Solar Design. Resource Smart. Retrieved from http://www.resourcesmart.vic.gov.au/documents/ENV031_02_Passive_Solar_Design.pdf Connection Online Pty Ltd. “Why is ventilation important?” Build. Retrieved from http://www.build.com.au/sustainability/passive-house-design/why-ventilation-important-3 Planning Services Special Projects Unit (2009). Guide 2 Harnessing Cooling Breezes. Townsville City Council. Retrieved from http://www.townsville.qld.gov.au/resident/planning/sustainable/Documents/Sustainable%20Housing%20Guide%202.pdf Sustainable Energy Authority Victoria. Air Movement Fact Sheet. Sustainability Victoria. Retrieved from http://www.sustainability.vic.gov.au/resources/documents/Air_movement.pdf Fitzgerald, J. (2011). Choosing a Ventilation System. Home Improvement Pages. Retrieved from http://www.homeimprovementpages.com.au/article/choosing_a_ventilation_system

Australian Building Codes Board 2010. Energy Efficiency Provisions for BCA 2010 Volume Two. ABCB. Retrieved from http://www.abcb.gov.au/education-events-resources/publications/~/media/Files/Download%20Documents/Education%20and%20Training/Handbooks/2010_EE-Handbook-BCA-2010-Vol2-web.ashx Adelaide City Council. Noise Technical Fact Sheet 6: Ventilation. Adelaide City Council. Retrieved from http://www.adelaidecitycouncil.com/assets/acc/Environment/noise/docs/noise_fact_sheet_6_-_ventilation.pdf

Barrett, S. (2012). Retrofitting for Sustainability, A Guide for Far North Queensland. Cairns and Far North Queensland Environment Centre. Retrieved from http://cafnec.org.au/download/publications/Retrofitting%20Guide_Final.pdf Air Exchange Asia Pty Ltd. Ventilation. AirExchange. Retrieved from http://airexchange.com.au/ventilation Building Code of Australia 2010 - Volume Two. Class 1 and 10 dwellings. Retrieved from http://www.scribd.com/doc/50987757/Building-Code-of-Australia-2010-Volume-Two-Class-1-and-10-dwellings Natural Strategies Group Pty Ltd. Use plants to remove toxins. Town of Cambridge http://www.sustainable.cambridge.wa.gov.au/garden/use-plants-to-remove-toxins Environmental Design Policy- Residential. City of Subiaco. Retrieved from http://www.subiaco.wa.gov.au/fileuploads/Residential%20Environmental%20Design%20Policy%20and%20Sustainability%20Checklist(1).pdf Eco-friendly living. District Council of Mallala. Retrieved from http://www.mallala.sa.gov.au/webdata/resources/files/11_07_06_ECO_info_environ_living.pdf A Solar Roof Vent Can Save You Money on Air Conditioning. Solar Energy for Homes. Retrieved from http://www.solar-energy-for-homes.com/solar-roof-vent.html Solar Roof Ventilation and Attic Ventilation. Solar Whiz. Retrieved from http://www.solarwhiz.com.au/ Department of Science, Information Technology, Innovation and the Arts. Alternative Fuels and Energy. Australian Technology Showcase. Retrieved from http://ats.business.gov.au/companies-and-technologies/environmental-technologies/renewable-energy/alternative-fuels-and-energy Keeping Cool. NABERS. Retrieved from http://www.nabers.com.au/page.aspx?cid=574&site=3 Retail Electricity Price Forecasts. Australian Energy Market Commission. Retrieved from http://www.aemc.gov.au/Media/docs/Information%20sheet-9110c5bf-385f-4ed4-8642-f9569133e97e-0.pdf Your Electricity Bill. Clean Energy Future. Retrieved from http://www.cleanenergyfuture.gov.au/helping-households/your-electricity-bill/

Solar Roof Fans 101. Solarvent. Retrieved from http://solarvent.com.au/index.php/faq