Lindsay Scott and his family moved into their new home in South Sound just over a year ago and since then have been keeping an eagle eye on their electricity bills to see if their home really delivers the energy efficiencies they planned.
So far, so good.
Their 3,340 square foot home in Vienna Circle offers energy saving at every turn – insulated walls and roof, a highly efficient air extraction system, high-energy air conditioning units, state-of-the-art Japanese Daikin condensers, a heat exchanger (Scott’s favourite item) and TiltCo windows and patio doors that effectively seal the house shut.
When the Scotts turn on their air conditioning, not a puff of that air escapes and no warm air from outside gets in either.
He offers a simple test to prove this is true. By placing one’s hand against the tiny crack of light between the impressively large wooden front door and its frame, there’s no air coming through that gap. However, when he turns on an small extractor fan in the kitchen, there’s a slight breeze. When he turns on the house’s central vacuum system, it feels as through a tornado is blowing through. When he turns them off, there’s no longer any air getting in.
“What you do is you build an envelop. Once you do, the house is airtight. You don’t let any air from outside in, unless you control that air,” he says.
“The way you accomplish that is with insulated roof and walls. That stops the heat from penetrating and stops the air from moving through the structure. That’s what we fight in the Cayman Islands where we have summer and a little bit of spring and then you go back to summer,” he says.
That gap at his door is the only place in the house where air can get in, if the windows and patio door are closed.
He acknowledges that there are probably plenty of people who want to live with fans and with their doors and windows open, but he says “if a person wants to live in an air-conditioned environment and doesn’t want to pay out something like $2,000 a month in the utility company, you need to make sure you have a structure built so that it can be air conditioned.”
“When people turn their air conditioner off, the house gets hot within half an hour and that’s because outside humidity has penetrated the house… In a normal house, you have constant air flowing through it and until you stop that air flow, you don’t stand a chance of air conditioning being successful,” he said.
The walls inside his house, built with insulated form blocks made of Styrofoam and filled with poured concrete, are cool to the touch when the sun is blazing, and even the insulated window, with its four layers of glass and 12mm of air between the outside three panes of the glass and the one interior pane, are also not hot. His window coverings are honeycomb blackout shades, which captures heat and prevents the heat of the sun hitting the glass panes from radiating through. The window frames are made of vinyl-covered steel.
When designing his home, he says the two most important things for him were hurricane resistance and energy efficiency. To kill two birds with one stone, he has the vents that take hot air and humidity out of the house through a shoot that goes down the length of the house and comes out in the ceiling of his ground-floor, open garage. With no vents in the roof or walls, rain in a hurricane or heavy storm cannot get into the vents. “My house is elevated so I can do that. I push it down underneath the house and straight out,” he says.
He keeps a file of all the Caribbean Utilities Company bills he has received since he got his first one in January last year.
He has worked out that he is paying 33 cents per kilowatt hour for the electricity he uses, or 41 US cents. “That’s nearly four times as much as people pay in the States where it’s about 11 cents per kilowatt hour,” he says.
Hence, he battles to use as few kilowatt hours as possible.
“My goal this year is to find ways to reduce my daily consumption,” he says. “The consumption on a daily basis is the number everyone in Cayman should be focused on, your kilowatts. Your CUC bill fluctuates with the number of days in the billing cycle and the fuel factor, so focus on your consumption and try to find ways to reduce it.”
“On average, my monthly bills have been $419.86,” he says, dividing the total $5,038.40 he has paid to CUC for the year by 12. His average daily consumption is 40.92 kilowatts hours per day, with a total of 14,937 kilowatt hours for the year.
Previously, when he lived in a 1,300 square foot condo at The Residence in George Town, less than half the size of his new abode, his bill for 33 days in and around December 2009, for example, was $335.90, using 36.15 kilowatt hours per day.
He says friends of his live in houses around the same size as his South Sound home who are paying $1,500 to $1,600 a month for their electricity. He says the money people save in smaller power bills will pay for those more expensive air conditioning units with higher SEER ratings and attic insulation that lead to those savings. It’s a win-win situation, he says.
Scott advises people to check their air conditioners to see if they are 10 or 11 SEER air conditioners, which have low efficiency and lead to higher electricity bills. In the United States, nearly a decade ago, SEER 10 air conditioners were banned and SEER 12 and higher became the national standard.
A SEER 10 air conditioner requires 30 per cent more watts than a 13 SEER of the same tonnage or output. That’s why it’s important for tenants and home owners to check what air conditioning units are installed, Scott points out, as many of the 10 SEER air conditioners that could not longer be sold in the US ended up on the Caribbean market.
His own air Daikin conditioning system is 31 SEER, which cost about 10 per cent more than a 16 or 18 SEER unit, but bring him higher efficiency and savings.
A tour of his garage, underneath the house, reveals what he says is perhaps his favourite item in the home – an Aquefier heat exchanger.
The heat exchanger captures waste heat discharged from the refrigerant cycle in an air conditioning or heat pump system, and transfers that heat into a water heater tank, creating low cost hot water for domestic use. It brings even further savings when pumped into a swimming pool if hot water is not regularly required at a home, he says.
Scott says using a heat exchanger will cut costs for the two most expensive electrical systems in a person’s home – air conditioning, which he estimates makes up about 70 per of a power bill, and water heating, which accounts for 12 per cent of the bill.
“If everybody on this island put a heat exchanger in their home, everyone’s electricity bills would go down,” he says.
Scott says his home design could be a blueprint for other more energy efficient homes in the Cayman Islands.
Here’s Lindsay Scott’s point-by-point advice on creating a home with smaller power bills.
Insulated Concrete Forms (ICF) walls
Insulated Concrete Forms (ICF) floors
VRV air conditioning system from Daikin
Insulated windows and doors
Insulate attic With spray foam from Icynene
Elevated to take advantage of the cooling effects of the breeze
The A/C condenser units should be placed in a well ventilated covered enclosure protected from the sun and rain
Install extractor fans to remove all heat and humidity from bathrooms
Install extractor fans above cook tops and ovens
Install a Quiet-Vent Ventilation System to boost the performance of the extractor fans