Solar air collection equals energy savings, increased productivity and reduced carbon emissions

A building’s air-conditioning system is typically responsible for around 50% of the base building’s energy consumption. The other 50% typically includes other services such as common area lighting, domestic hot water, lifts, etc. As such, any reduction in air-conditioning energy consumption or efficient energy utilisation will offer significant savings in total building energy consumption and carbon emissions.

Night purging, displacement ventilation, positive input ventilation with 100% fresh air intake (solar air collectors), high thermal mass materials and a cogeneration plant could significantly contribute to the health of occupants, as well as the reduction of carbon dioxide emissions and energy consumption of the building. The use of all these initiatives will reduce carbon emissions to 44% of a 4.5 star building under the Australian Building Greenhouse Rating scheme.

Building loads determine the heating and cooling requirements of a building and come from sources such as occupants, equipment, lighting and the sun. A typical large-scale building can have hourly energy loads up to the following: lighting - 95 kWh; occupants - 45 kWh; equipment - 155 kWh (summer solar 60-110 kWh, mid-winter 30-65 kWh). On a monthly basis, this could lead to a mean usage of between 60,000 and 80,000 kWh.

Using a thermal (solar air collector) panel system for both night flushing for cooling and daytime solar absorption for heating introduces 100% fresh air into the building, thereby flushing out all contaminated air without mixing. This greatly increases air quality, wellbeing and productivity of all occupants. Following this, maintenance costs are greatly reduced due to minimal hourly use of boilers/chillers.

As most large-scale buildings are built on concrete and other reasonably good thermally absorbing materials, they are capable of storing and releasing large amounts of energy (sensible heat). In summer, the building will store the coolness of the night and use it to cool the building during the day. In winter, the building will attain the solar heat energy and use it to maintain higher core temperatures at night.

“Thermal mass, correctly used, moderates internal temperatures by averaging out diurnal (day/night) extremes,” says Chris Reardon et al on the Australian Government website YourHome. “Poor use of thermal mass can exacerbate the worst extremes of the climate and can be a huge energy and comfort liability.”

The intent of a ‘green’ building is to minimise the emission of greenhouse gases, namely carbon dioxide emissions, through efficient energy usage. This will be dependent on energy utilisation between sources such as electricity, gas, solar, wind, a cogeneration plant, etc.

United Nations Secretary-General Ban Ki-moon has stated, “Leaders must act. Time is not on our side.” He says that quick, decisive action will build a better and sustainable future, while inaction will be costly.

“The buildings of our cities are our businesses, the businesses of our cities are our leaders and it is time for simple, cost-effective change.”

In the state of Victoria, gas has a CO₂ co-efficient of 0.21, which is much less than the 1.34 co-efficient for electricity. This means that electricity pollutes about 6.4 times more than gas and electricity usage is most undesirable.

It is obvious that using a thermal passive input ventilation system with 100% fresh air improves longevity and cost-effectiveness of the system. The system offers advantages such as:

• Reduced carbon emissions. CO₂ emissions are reduced to 40% of a 4.5 star building.
• Air quality. The system provides 100% fresh, non-recycled air, as well as using the benefits of continuous ventilation to flush warm contaminated air out instead of mixing it within the space.
• Equality of access. All occupants have access to the cool ceiling above, and floor vents are evenly distributed to passively prove a more even temperature throughout the space.
• Increased productivity. Through the reduction of noise, the increase in air quality and the even distribution of cool air, occupants are healthier, more comfortable and more productive, with an increased state of wellbeing.
• Maintenance. This is reduced for a chilled night flush system as there are fewer moving parts.
• Increased life span. The chilled night flush system has an increased life span because of reduced plant loads and fewer maintenance problems.
• Space savings. Thermal heat and night flush (solar air collectors) systems eliminate the need for additional internal high-volume ductwork, minimising ceiling void requirements and increasing opportunities for refurbishment as well as increasing net leasable areas opportunities. All solar air collector systems can be retrofitted and adapted to existing air ventilation systems.
• Energy efficiency. Friction losses and lagging are eliminated by the system and the building fabric contributes to the cooling system.
• De-humidification. With solar air collectors, all daytime air has the benefit of dehumidification, greatly reducing the possibility of increased condensation.

To improve a building’s energy savings even more, apply secondary external shading to northern/western walls and external screening/shading to glazed areas, and utilise thermal (light-coloured) paints.