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6 Types of Cool Roof Technology

Posted on August 15, 2023 by dishanth

Cool Roof Technology: a Low-cost Way to Reduce Energy Consumption and Carbon Emissions

Want a huge decrease in carbon emissions, a reduction in summertime cooling costs and a more efficient home? Cool roof technology can do all that. Cool roof technology has the potential to eliminate billions of tons of carbon dioxide at a very low cost.

If you’ve ever spent time on a black asphalt roof or up in an attic during the heat of summer, you understand how much heat energy is added to a home during summer months. This is heat that many of us pay to remove by using air conditioners and other means.

But what if, just by a better design and choice of materials, we could have a far cooler house that uses far less electricity each month? That is what people in the Mediterranean and other hot climates have been doing for centuries. White paint and chimney-style ventilation that distributes cool air from lower areas of the house are low-tech examples of cool roof technology that works.

Modern cool roof technology is similar. Most are just like regular roofs but are designed to reflect sunlight and shed heat, to keep buildings cooler in the summer. According to a study by the National Renewable Energy Laboratory (NREL), cool roof technology could reduce energy consumption for cooling by up to 20%. The study also found that energy savings from cool roof technology could eliminate up to 1.4 billion tons of carbon dioxide emissions annually in the United States. The equivalent of taking 300 million cars off the road!

According to Lawrence Berkeley National Laboratory, if all North American cities with populations over 1 million people adopted cool roof technology, air conditioner use would fall by one-third.

The Human Cost of Heat

The savings aren’t just in terms of money and carbon emissions. Climate change has disproportionately increased temperatures in urban areas. An urban landscape largely covered in asphalt, concrete and black roofing materials is far hotter than one covered in greenery or reflective materials, a phenomenon known as the urban heat island effect.

The urban heat island effect is the phenomenon of cities being warmer than surrounding rural areas. This is because cities have more dark surfaces, such as black roofs, which absorb sunlight and heat up the air. The heated air then rises, creating a convection current that draws in cooler air from surrounding areas. This process can lead to increased temperatures in cities, which can have a number of negative consequences, such as increased energy consumption for cooling, decreased air quality, and increased heat-related illnesses and deaths.

Black roofs also radiate energy directly into the atmosphere. This energy is then absorbed by clouds and trapped by the greenhouse effect, further contributing to global warming.

Type Depends on Location Climate

There are a number of different types of cool roof technology available, including:

Reflective roofs: Reflective roofs are the most common type of cool roof. They are made of materials that reflect sunlight, such as white or light-colored tiles, metal roofs, or paints. Reflective roofs can reflect up to 90% of the sun’s heat, which can help to keep buildings cooler in the summer.
Evaporative roofs: Evaporative roofs are made of materials that allow water to evaporate, such as clay tiles or metal roofs with a water-absorbing coating. As the water evaporates, it cools the roof and the building below. Evaporative roofs can be effective in hot, dry climates.
Phase-change materials: Phase-change materials are materials that change their state from solid to liquid and vice versa. When these materials change phase, they absorb or release heat. Phase-change materials can be used in cool roofs to store heat during the day and release it at night. This can help to keep buildings cooler in the summer and warmer in the winter.
Cooling paints: Cooling paints are paints that are applied to roofs to make them more reflective and to help them cool down. Cooling paints are effective in hot, sunny climates and typically contain titanium dioxide, a highly reflective pigment.
Cooling granules: Cooling granules are small, reflective beads applied to roofing materials like shingles. The granules reflect sunlight and help to keep the roof cooler. Like cooling paints, cooling granules are most effective in hot, sunny climates.

Green Roofs are Cool Roofs

Another type of cool roof technology is the green roof. Green roofs are made of a waterproof membrane with a layer of soil and vegetation on top that helps to insulate the roof and reflect sunlight. Green roofs can reflect up to 70% of the sun’s heat, which can help to keep buildings cooler in the summer. In some cases, they can provide vegetable gardens or just a nice place to sit and enjoy the feeling of being surrounded by nature – while in the city.

Green roofs also have the effect of providing bird and pollinator habitat as well as reducing stormwater runoff. Because of the benefits, many cities are now mandating the installation of green roofs on new construction. New York, San Francisco, Chicago, Seattle and Portland all require green roofs on new construction on buildings with roof areas over a specific set size. That said, retrofitting an existing building is often cost prohibitive due to the structural requirements to support the additional weight.

Cool roof technology is a promising way to reduce greenhouse gas emissions and improve the energy efficiency of buildings. As the technology continues to develop, the potential for cool roofs to reduce carbon dioxide emissions will likely increase.

This is an easy way to make big gains in carbon reductions, saving homeowners and businesses money. Something we can all get behind.

Source Happy Eco News

How Singapore is turning multi-storey car parks into farms

Posted on August 3, 2022 by dishanth

Eyleen Goh runs a farm from the top deck of a car park in Singapore.

And this is not a small operation – it supplies nearby retailers with up to 400kg of vegetables a day, she says.

“Singapore is quite small but we have many car parks. It is pretty much the dream to have farms [here] to meet the needs of residents in the community,” she says.

Urban farmer Eyleen Goh farms among high-rise buildings. BBC

At least a dozen of these rooftop farms have now sprouted up across the South East Asian city state.

The government started leasing out the unusual plots in 2020 as part of its plans to increase local food production. The country of 5.5m people currently imports more than 90% of its food.

But space in this densely populated island nation is scarce and that means land is not cheap. Singapore has some of the world’s most expensive property.

One farmer told the BBC that the high cost of his first car park plot meant that he had to give it up and move to a cheaper location.

When BBC News visited Ms Goh’s farm, which is about the third of the size of a football field, operations were in full swing.

Workers were picking, trimming and packing choy sum, a leafy green vegetable used in Chinese cooking.

At the other end of the facility meanwhile, another employee was busy re-potting seedlings.

“We are harvesting every day. Depending on the vegetables we are growing, it can range from 100kg to 200kg to 400kg per day,” Ms Goh says.

She says starting the farm cost around S$1m ($719,920; £597,720), with much of the money being spent on equipment to help speed up harvesting.

Workers harvesting vegetables at Eyleen Goh’s rooftop farm. BBC

Although she has received some subsidies, Ms Goh says her business is not profitable yet.

She has 10 employees and pays a rent of around S$90,000 a year for the space and another car park site, which is still being set up.

“Our setting up period happened during the Covid pandemic, so logistics were way more expensive and took a longer time,” Ms Goh explains.

“Moreover, this was the first rooftop car park tender awarded [by the government] so the process was very new to everyone,” she adds.

Singapore’s rooftop farmers are also finding other ways to make money.

Nicholas Goh, who is not related to Ms Goh, says he has managed to turn a profit by charging people a monthly fee to harvest vegetables at his urban farm.

He says the idea is particularly popular with families who live nearby as “it is a community kind of approach, rather than a commercial approach”.

However, another urban farmer, Mark Lee, says high costs have driven him to move to an industrial building that charges a “negligible” i.e. lower rent.

“Vegetables are ultimately just vegetables. You can get it at the freshest and best quality but there is limitation to how much one would pay. We’re not talking about truffles here,” Mr Lee says.

‘Existential issue’

Rooftop farms are not the only way Singapore aims to increase the amount of food it grows.

Most of the country’s home-grown produce comes from high-tech facilities that are heavily subsidised by the government. It had 238 licensed farms in 2020, according to official figures.

Some of the farms are already profitable, and can expand their production to increase profits, the Singapore Food Agency (SFA) says.

“Food security is an existential issue for Singapore. As a globally connected small city-state with limited resources, Singapore is vulnerable to external shocks and supply disruptions,” an SFA spokesperson tells BBC News.

“This is why it is important that we continuously take steps to secure our essential resources,” the spokesperson adds.

The farms are located in public housing estates. NATURE’S INTERNATIONAL COMMODITY

Earlier this year, the issue of food security came into sharp focus in Singapore when several countries in the region banned or limited exports of key foods.

Governments reliant on imports tried to protect their food supplies as the Ukraine war and the pandemic pushed up the cost of everything from staple foods to crude oil.

By 2030, Singapore aims to produce 30% of the food it consumes itself – more than three times the current amount.

Professor William Chen of Singapore’s Nanyang Technological University says more support should be offered to urban farms.

“There are measures in place such as productivity grants from SFA, and regular farmers’ markets to encourage consumers to buy more local produce,” says Prof Chen, who is a director of the university’s food science and technology programme.

“Perhaps helping local farmers to adopt simple technologies… may be considered,” he says.

However, Sonia Akter, an assistant professor at the Lee Kuan Yew School of Public Policy, believes high operating costs are likely to remain a major challenge for urban farmers.

“Singapore is offering a lot of subsidies and financial support to entrepreneurs who are working in this space,” she says.

“The question is whether these farms will be able to operate and be commercially viable when the government support stops flowing.”

Back on a rooftop surrounded by tower blocks in the midst of Singapore’s urban sprawl, Ms Goh may seem a world away from traditional agriculture.

However, she echoes the sentiments of generations of farmers who have come before her: “Giving up is not an option. The more challenging it is, the more rewarding it will be.”

Source BBC