On our vehicle, the two escape roof hatches when opened let massive amounts of light into the living space. I am replacing the plastic opaque roof hatches with double insulated skylight style (they still open, and provide ventilation), so we have constant natural illumination.
The vehicle itself has an 18" roof raise, and 3" of foam insulation on the walls/ceiling and 2" on the floor. The underbay is insulated, and has heating elements for the tanks, as well as ducting for heat system in that area to keep things warmer than outside.
There are six primary viewing windows, approximately 16"x30" cut in the kitchen and passenger area that are double pane. The windshield, two escape door windows, and rear windows are original school bus single pane glass.
As the vehicle sits right now, when ambient temperature is in the 20 degree F range overnight, I am able to keep the interior ambient temperature as measured from 3' off the ground to the ceiling at 70 degrees with a single 1200 watt forced air space heater.
Below the 3' mark, the temperature drops to about 60 degrees, and the driver area up front stays consistently around the 60 degree mark. Any opening of the door for entry and exit with that tiny space heater takes about 20 minutes to recover the temperature at those outside temps.
If I had an actual heater in place with higher capacity air exchange, I would expect the entire vehicle to have far less gradient and stay comfortable with a 5-7k btu heater at those temperatures.
Since a 10-20k btu heater is easy to come by, I have few concerns regarding keeping the bus warm in temperatures below freezing. I DO have concerns with ensuring the air systems and engine are operational and work safely at low temperatures.
I feel that a wood stove is only useful if you plan on parking for periods of time where wood can be had easily. The energy density of wood makes for a cumbersome process if you're on the move more often.
For stationary heating, diesel fuel (heating oil) or propane would be my heating energy of choice. The vehicle itself generates plentiful amounts of waste heat when underway, so heaters from the coolant loop work fine when driving.
I don't remember who built it up, but someone had cut the grooves into the floor of their bus for heated water lines for radiant floor heat. If I had more budget, I would install twin coolant heaters connected to a valve manifold that allows me to select regions for heat, including the engine block if desired.
The plumbing may be mildly complex, but the idea of choice of heating the vehicle from engine heat or coolant heater, and the choice of dispersing the heat through radiant floor, heater core, or hot water seems ideal.
Originally Posted by JHands
The roof raise and fabrication is a daunting task that I'm not sure I want to tackle. And he has hardly any windows in it. I get why, but just saying it must be dark inside at most times.