The only solutions that works for most people are to add a tapered, 28" wide at shoulders and 18" at the feet, foam pad under your sleeping bag or to attach an insulation blanket comprised of down or synthetic to the bottom. The thickness of the pad or the under insulation is dependent on the temperature you need to achieve. Loft equates to temperature rating. If you want a quilt capable of keeping you comfortable in sub-freezing temperatures you better be in the 2.5” loft range. The equivalent foam padding would need to be approximately 1" thick. Insulation blankets are available from multiple vendors.
Backpack Gear Test started a study on the Hennessy Super Shelter. 3 people published their initial and field reports. The results were mixed with one of the testers claiming that the system only lowered the allowable temperature to about 50 degrees. The manufacturer then asked that the test be started over with additional items added to the system to provide warmth.
The Backpack Gear test statement was, "This test is currently suspended. The testers didn't receive the entire system due to an oversight, and the reports as they exist may not (and probably do not) accurately represent the Super Shelter system. The following was received from Tom Hennessy by way of explanation. We are working to resolve this difficulty. The test may have to be redone after the rest of the items are received. We apologize for any inconvenience to our readers.”
The testers didn't receive an important part of their winter testing gear which we inadvertently did not ship. Please ask the testers not to resume testing until they receive the missing parts.
We're sending two different accessory pads to add more insulating materials where it's needed most:
1/ Torso Pad - placed on top of the underpad to double the thickness of the insulation on the torso.
2/ Kidney Pad - placed on top or under the torso pad right on the kidney area to triple insulation where most people get chilled first.
Both torso and kidney pads do not need attachment points because two pieces of open cell foam are very grippy and do not shift when placed in position. When installing the torso pad and kidney pad, we also suggest experimenting by layering a space blanket between the pads.
Although not supplied with the cold weather system, at temperatures below 50 degrees depending on the individuals' sleeping gear and metabolism, the space blanket is an important part of the system.
The space blanket should be placed on top of the foam pads to keep the moisture barrier on the warm side of the insulation to minimize condensation.
Also, we're sending an OverCover which was designed for dry below-freezing weather testing - but we are getting reports from early adopters that it is also being used with good results for colder above-freezing temperatures. This is an optional accessory and the set up tips are already listed on the 4 season system bag. We intended to test this separately but realize it could take another year to obtain the results so we're including it with the pads.