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UAE: Why some residents keep AC on even when they're not home during long holidays

Returning to a cool house, instead of baked walls, is welcoming however, balancing comfort and energy conservation is crucial

Should people leave their air-conditioners (AC) running when they are not home during holidays? Opinions among UAE residents differ: While some advocate turning the AC on, others never feel the need. Khaleej Times spoke to experts to settle the matter.

"The ideal situation to reduce energy consumption while going on a long summer holiday is to switch off the air conditioner (AC)," said Dubai Electricity & Water Authority (Dewa). "However, this may result in drawbacks such as fungus formation, bad smells, and damage to paint, furniture, and electrical/electronic equipment due to the increased temperature and humidity inside homes, the utility company added in a statement to Khaleej Times."

To many, being away on holiday might mean saving on utility bills — yet some choose to keep their ACs running even if it means returning to 'gigantic and electricity bills'.

"Rotting and condensation from keeping the AC off for a long time can cause damage to furniture and walls. Hence, we keep ours running when we go on holidays," said Abu Dhabi resident Magalie H.

Shun Khin Shun Lae Tha, a Myanmar expat, said: "In 16 years in the UAE, I've always turned off my AC during holidays; never felt it was necessary. I would be more worried about the extra utility cost, leakage that may occur, and the waste of energy."

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What humidity can do

"While it might seem cost-effective to switch off your AC during vacation, experts unanimously agree that it's better to keep them running," said Hisham Jaber, founder and head of strategy and business transformation of The Healthy Home.

Magalie, a Lebanese expat, learnt it the hard way. "We went on a vacation and returned home to mould on the walls and ceiling. Luckily, it hadn't spread much, and we were away only for a week."

Imagine if the growth continued for three weeks or longer. There have been instances where residents returned to find their homes covered in mould, forcing them to discard everything, including furniture. Despite hoping to save on utility bills, they ultimately paid a steep price.

Dinesh Ramachandran, technical and SHE manager at Rentokil Boecker, explained how humidity can damage homes. "In summer, when villas and apartments are left without the AC running, humidity can build up, leading to mould growth, damage to upholstered furniture and carpets, and potential health risks for occupants."

Hisham from The Healthy Home agreed, stating: "Running your AC continuously helps maintain optimal humidity levels, especially in humid conditions like Dubai. Extreme heat can damage electronics, artwork, and indoor plants. Consistent airflow also prevents moisture build-up that leads to mould and mildew."

The right temperature

Setting the correct AC temperature before flying out is crucial. It conserves energy, reduces costs, maintains a healthy indoor environment.

Dewa said, "In general, turning up the AC is one of the easiest ways to increase the efficiency of electricity consumption. People can reduce their electricity consumption by up to 5 per cent by increasing AC thermostat temperature by just 1°C.

"We recommend using programmable thermostats or smart AC controls to automatically adjust temperatures throughout the day based on resident’s schedules. This prevents needless cooling when the house is empty."

Dinesh recommended turning the AC on between 26°C and 28°C. Residents with a programmable thermostat can switch the 'fan-only option' which will turn on the AC when needed. Otherwise, residents could use the AC mode with an auto cut-off setting while on vacation.

Talking about other precautions residents should take to keep their homes safe from moulds and condensation, Dinesh added: "Leave bedroom and kitchen doors open to help air circulation. Clean AC filters quarterly and have ducts cleaned by a NADCA-certified service provider. Use a programmable thermostat for efficient energy use."

According to Dewa, residents may replace old ACs to get a more energy-efficient model. "These new units are more efficient and benefit the environment. Before buying, compare ESMA/MoIAT energy labels. An air conditioner with a 5-star or 4-star rating is more efficient at up to 30 per cent than a 1-star air conditioner.

High electricity bills

Returning to a cool house, instead of baked walls, is welcoming. However, balancing comfort and energy conservation is crucial, as residents also risk high electricity bills after returning home.

Born and raised in UAE, Indian expat Renuka Bhatia would never keep the AC running during her long summer break. "We never did that, nor did our friends and relatives, and none of us faced any issues. Only when we had a pet in the house we started turning on the air-conditioner."

The 60-year-old said her utility bill had been more or less the same. "Our pet-sitter would regulate it, turning it from fan mode to AC."

Long-time UAE resident Cinderella Mounir leaves the AC on during her vacation in her two-bedroom apartment. "However, the downside is a gigantic, very expensive electricity bill and AC maintenance once I'm back. I come back to Dh1,200-1,500 utility bills. I'm lucky to have a pet-sitter who looks after my cat, ensures the AC works fine, and airs the apartment every other day," said the Egyptian.

Cutting electricity costs

Magalie installed smart AC controllers in her three-bedroom (+ maid's room) villa that activate only when the temperature deviates from the set point. "As a result, our electricity bills remain consistent year-round, typically ranging between Dh1,200 and Dh1,800, except during winter when they vary slightly. Throughout fall to spring, when the AC is in use, we maintain a constant setting of 24.5°C on the controllers without adjusting them frequently."

To manage electricity bills, consider setting your thermostat between 26°C and 28°C. This can be particularly effective if you have a programmable thermostat. If not, set the temperature to 28°C on fan mode at the lowest setting with the auto function.

According to Dewa, close curtains and blinds before heading out on vacation; this helps minimise solar heat transfer and avoid humidity. Ensure that the condensate water drainage is clear, the AC filter is clean, and you have adequate remote monitoring. Through Dewa's ‘Away Mode’ feature on app, customers can monitor their consumption while they are outside or travelling.

Leaving your AC on while you're away can actually be more energy-efficient than turning it off completely. This prevents the unit from working harder and longer to cool down a warm house when you return.

AC's energy consumption

Dewa recommends scheduling regular maintenance for cooling systems to ensure they work efficiently. "One way to achieve this is to clean air conditioning filters every two months (monthly in summer) and replace them regularly. This can significantly increase energy consumption efficiency and help maintain comfortable indoor conditions."

Regular cleaning and maintenance of outdoor units can positively impact air conditioning energy usage. Additionally, the correct placement of the outdoor units can enhance the performance of the split systems. For instance, they should be positioned to provide shade and adequate ventilation, steering clear of areas that restrict air flow, like narrow corridors. Do not install multiple outdoor units in close proximity (avoid blowing one unit's exhaust air into another).

Moreover, gaps in windows and doors can leak cold air. This means that the air conditioner will have to work extra hard to maintain the ideal temperature at home. Weatherstripping is an easy and cost-effective way to increase cooling efficiency in your home.

Let the air flow

If you are still not convinced about leaving the AC running, consider asking a friend or neighbour to turn the unit on for 30 minutes to an hour daily.

If that doesn't work, using exhaust fans in kitchens and bathrooms with doors open can help manage humidity levels. However, effectiveness may vary based on factors like apartment location, exposure to sunlight, and floor level within the building.

Leaving your cupboards and cabinets wide open can facilitate better air circulation within your living spaces. Keep doors of bedrooms also open; this helps maintain a more balanced indoor environment, particularly during warmer periods.

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