As we replace shorts and flip flops for sweaters and jackets, we are inevitably going to have to bite the bullet and flip that switch over to “heat” to take the chill out of the air in our homes. One of the most common questions we get from clients is whether they can have radiant heat in their new energy efficient home. After all, it’s cozy, particularly in the dead of winter when no one wants to slide out of bed in the wee hours of the morning and traipse across a jarringly chilly floor. The heating process, however, is quite different when it comes to a carefully-designed energy efficient, net zero or net positive home.
Energy efficient homes are complex organisms with quite a few moving parts. Minimizing the dependence on expensive electricity or limited natural resources, our homes take advantage of solar gain, free heat provided by the sun, even during its infrequent appearances in the winter. The UV portion of the light turns into heat upon reaching the glass surface, which then transmits to the inside. Picture your car in the parking lot on a sunny winter day; it still gets really toasty on the inside.
This same scenario also applies to your energy efficient home. If you set your thermostat to a comfortable 72 degrees, the sun adds heat to that. What will your radiant heat system do? The thermostat will recognize the increase in temperature and send a signal to the heat source (typically a gas furnace) to stop heating the house. That sounds simple, but the reality is, the warm floor doesn’t cool down fast enough due to its sluggish nature. Your house can then overheat, and we have even seen people turn on their AC in the winter in an attempt to bring the temperature down to a tolerable level! Another disadvantage is that radiant heat is a water-based system and you would still need a second system for air conditioning.
The limitations behind this traditional heating system are why you need something more eloquent, with a fast response time. We recommend heat pumps, as they are air-based and very responsive. And as a bonus, the mechanical ventilation in a low energy building distributes the free, warm air throughout the house. And believe it or not, a heat pump generally costs less than a traditional heating and cooling system! It’s nothing short of genius!
What about the tried and true gas furnace?
In theory, gas furnaces can work, but there’s a catch: we believe that it is our responsibility as humans to avoid using fossil energy, a limited resource that has a very negative effect on our climate.
From a functional perspective, furnaces need a certain workload in order to operate at their maximum efficiency, which is pretty pathetic in comparison to modern alternatives. A state-of-the-art gas burner is about 90% efficient. That means that it gets 0.9 kW of heat out of 1kW of energy. 90%, not bad, you might think. Wrong! A modern heat pump generates 3kW out of 1 kW of energy. That’s 300% efficiency. Yes, your math is correct, this system emits more energy than it uses; that is what’s known as net positive! The real issue is that efficient homes need very little thermal energy to stay warm and a conventional furnace will never run at its ideal performance levels. That would lead to more energy loss and higher bills! Additionally, there is the cost of connecting your home to the gas supply.
But we need central AC in the summertime, right?
A conventional home typically has both, heating and air conditioning, two separate systems that are both very inefficient. Our homes don’t need A/C simply because heat pumps can do both, heat and cool the home just by reversing the direction of the heat flow. In winter, they extract thermal energy from the surrounding air (even on the coolest days) and from the warm inside air during the summer. No longer is there a need for two disparate, inefficient systems that cost money and are not environment-friendly.
If you have any questions on how to build your energy efficient dream home, drop us a line! We’d love to chat!
