HVAC Control

The heart of the active HVAC control is the usual Heater/AC installation in the attic, control is achieved by means of an RCS networked thermostat.  It interfaces with Stargate through an interface box and the RS-485 port.  The thermostat mounts on the wall and offers the usual functions but it is completely monitored and controlled by Stargate.

RCS Networked Thermostat System

Besides the active and energy intensive conventional HVAC system, I've been trying to utilize passive control where possible.  To reduce cooling costs I utilize ambient air through motorized skylights and a whole house fan.  The skylights open to vent hot air from the high lofted ceilings, or act as an inlet for the Whole house fan which pulls cooler air from outside and blows the hot air into the attic and out of the attic vents.  This technique does a remarkable job of cooling the house, provided the ambient temperature is at or below your comfort set point.  On low humidity days it can even be hotter out than your set point since the slight breeze can make you "feel" cooler.

Velux Motorized Skylights and Blinds

These skylights are easily controlled by Stargate and its infrared interface. Additional passive HVAC control is afforded through the use of motorized blinds and curtains.  All blinds and curtains are programmed to block out direct sunlight during the heat of the day. (unless of course I don't want them to!)

Whole House Fan and Skylight Controls

Circulation is controlled through the use of ceiling fans mounted in the bedrooms.  Not very sexy but often overlooked are the bathroom fans.  They extract air from the bathrooms and vent them to the outside and aid in circulation.  Hey, every little bit counts when in passive mode.

Circulation Control

An important element of HVAC control is a good outside temperature measurement.  I use this one from Automated Environment Systems this is their ATP-3000T19E model which gives me 1 degree F resolution with Stargate's 8-bit analog to digital conversion.  It is mounted on a block of foam to thermally isolate it it from the house.

Outdoor Temperature Sensor

Now comes the tricky part, integrating each of these functions based on indoor and outdoor temperatures to optimize cooling, still working on this one!