High Efficiency Heating And Cooling

We’re used to having two “mechanical” systems in our homes, one to heat and one to cool. Whether your heating system is state of the art radiant heat solution to the little electric heater you plug in next to you. For cooling the same applies, from the most advanced central air model to a simple window unit, these serve one function, that is to cool your living space. 

According to the U.S. Department of Energy, heating and cooling our homes accounts for more than half of the energy use in a home on average. Considering how costly these systems are to run, many people resort to leaving their house warmer than they would like in the summer, and cooler than they would like in the winter. We trade off our physical comfort for savings in our wallet.

What if there was another way? A way of keeping ourselves and our family comfortable, without being scared of the utility bill? What if that way happened to be environmentally friendly as well? Fortunately there is a way, welcome to the world of high efficiency!

Heating:

Regardless of the way you heat your home, whether it be a furnace or boiler, with gas or oil, there’s one measurement that defines how efficient that unit is, and it’s called AFUE (Annual Fuel Utilization Efficiency). The highest rating possible is 100, what this basically measures is how much of every dollar you spend on fuel, goes to heating your home, and how much is lost to inefficiencies. For example, a unit with 96% AFUE loses only $.04 per dollar spent on fuel, whereas a unit with 80% AFUE loses $.20 per dollar spent on fuel. Clearly 96% is better than 80%. Every home is different and some may require more labor than others to accommodate a highly efficient boiler/furnace, so please check with your contractor.

Cooling:

There are several factors when determining the efficiency of cooling equipment. A very popular measurement is SEER (Seasonal Energy Efficiency Ratio). There’s no limit on SEER, but the minimum allowed by the EPA is 13 SEER, with higher end units coming in at around 18 – 24 SEER.

Another important factor in cooling is the compressor. The compressor is the “heart” of an AC system. It compresses and pumps the refrigerant throughout the entire system, and it is the biggest energy user by far. Most air conditioner compressors are single stage, which means they’re either on or off. Picture a car that you can only either floor the gas or floor the brake, no in between. Better air conditioners have two stages, a high and a low. Most of the time the system will run in the low stage, saving you money, and only turn on the high stage when needed. The best air conditioners are what’s called variable speed. A variable speed compressor has anywhere between 65 and 85 stages! These compressors act like a dimmer switch on light. With so many stages, your air conditioner is only working as hard as you need it to at that moment. An added benefit is that a compressor with so many stages will often run on low, rather than shut off and restart later. This avoids the massive surge in electricity required whenever starting a compressor, saving you even more money.

Heating & Cooling in one:

There is a solution that provides both heating and cooling in one. To understand this, we have to understand how an air conditioner works. An AC takes the heat (energy) out of a room, and brings it outside to dissipate. The reason why your air conditioner can make your room cool, even when it’s 110° outside, is because the AC is drawing the heat out of your 78° room, and compressing the refrigerant until it’s hotter than the outside. Hot goes to cold, so the heat is removed and cool refrigerant goes back to your room.

Since the principal of an AC is to take heat (energy) from one place and put it in another, what if we ran an AC in reverse? What if we drew the heat from outside, and put it in a room that needed it? We can, and it’s called a heat pump. These units provide cooling in the summer, and heating in the winter. Be careful though, depending on how cold it gets where you live, your heat pump might not provide enough heating to get you through the winter, in which case you’ll still need a boiler or furnace to back it up. Not all heat pumps are equal, low end central air units can provide sufficient heating only to 55°, higher end units can provide sufficient heating down to 0°. With mini-splits, regular units can draw sufficient heat down to 5°, while stronger units are able to draw sufficient heat down to -10 °.

As with AC’s, heat pumps also have a SEER rating for when they’re in cooling mode. In heating mode, the rating we use is HSPF (Heating Seasonal Performance Factor). Once again, the higher the better, with the most efficient units coming in between 9.5 – 10.5 HSPF.

The Most Efficient Heating & Cooling System:

Ultimately, the most efficient system to have is a variable speed heat pump, with a high AFUE boiler/furnace as a backup for the coldest days. Here in the NYC Metro area, with our temperatures, a heat pump can heat a home for the Spring, Fall, and most of the winter, only turning on the boiler/furnace for a couple weeks a year. This system should also be “Dual Fuel” enabled and have a thermostat that can control this. Dual Fuel is the ability to run either the heat pump or the boiler/furnace for heat, and switch back and forth based upon which system will provide the most efficient heat at the current temperatures. To decide which is more efficient at certain temperatures, we use the COP (Coefficient of Performance). The COP tells us how efficient the heat pump is at transferring heat versus the amount of electrical power it consumes. Once more, the higher the better with highly efficient heat pumps having a COP between 2 – 3 at 5°. The system will automatically switch which unit is supplying the heat, the homeowner doesn’t have to do anything.

Since we know that heating and cooling our home accounts for the majority of our energy expenses, from our electric bill to our oil/gas bill, we want to do something about it. With the system described above, you can have peace of mind knowing that we are using the most efficient equipment and using the least amount of energy possible. It’s good for your wallet and it’s good for the environment. The biggest question I get is, “How much more expensive is this than a traditional non-efficient system?”. Typically, the return on investment is somewhere between 4 to 8 years, but these are not typical times. Utilities across the U.S. are offering incredible rebates for heat pumps and highly efficient boilers/furnaces. Depending on what your utility rebate is, it’s actually be cheaper to buy the highly efficient system than the traditional non-efficient system!