|To Just Homes, the house is a living, organic
system. And the mechanicals are a critical part of this system – think
of them as its lungs and heart.
For new construction in particular, we
begin by reducing the overall heat load with features such as…
Next, you need a ventilation system to provide
fresh air and exhaust stale air.
a well insulated / air tight exterior shell
to reduce heat loss,
southern exposure (window fenestration)
for solar heat gain and
mass (double drywall) to buffer
the day time heat gain with the night time heat loss (like an adobe style
Our systems go one step further.
We use a separate small diameter duct
system to pick up exhaust air from washrooms, kitchens, laundry rooms,
etc, and bring it to a central air-to-air heat exchanger.
This device (see diagram) then recovers
heat from the warm outgoing airflow and uses it to temper the incoming
fresh air. The whole thing is known as a Heat-Recovery Ventilation
system, or HRV.
The heart of our mechanical system is the
"fan/coil” connected to the supply and return air ducts for your house.
This is simply a conventional furnace fan, combined with a coil like the
radiator in your car.
fan/coil has two functions. The first is to distribute solar and
internal heat gains throughout the house, including heat recovered through
the HRV system.
The second is to actually heat that
air when required – which means it needs a heat source.
Does that mean a furnace?
The fact is, with all the elements we’ve
designed in to reduce the load, most homes can be heated using nothing
more than their domestic hot water (DHW) heater as the heat source.
This way, one system provides both DHW and home heating.
Hot water from the tank is circulated through
the coil. The fan then picks up this heat and distributes it through out
the house. This can be supplemented by a storage tank connected to a roof
top solar collectors, wood stove with water coil, etc.
With a second coil connected to an outdoor
air conditioning unit, the fan/coil unit can also be used to cool
Here's how it all might look in a complete
You may at this point be wondering how
many PhD’s it takes to operate this system.
Luckily, it’s as simple to operate as any
conventional home. The system uses a standard thermostat, combined
with an adjustable whole house sensor to control the HRV system.
Our whole-house mechanical system is completely
assembled from “off the shelf” components, and any competent service person
will have no trouble installing or servicing it. In fact, in our experience
heating contractors are generally delighted with the simplicity and intelligence
of the system.
But this is all aimed at new construction
projects. What about renovations and retrofits?
to see how we adapt these ideas to an existing home heated by electric