I suggest add some “cloth” to heatbed !
to reduce backside heat( that probably affects other components behind heatbed )
Cork works very well for that.
It’s good to get suggestions like this out there. I use reflective insulation. Some people use cardboard with aluminum foil stuck to it. Basically, you want the heat to go up, and keeping conducted and radiated heat going up improves heat up times.
Somehow this solution also enlarge the heat lose time(in other words ,reduce the total heat time), so it must save lot more energy.
I use cardboard with aluminum tape used in ventilation duct work. It hold up good. I’ve seen wool being used, which also should work fine. You can also get foam mats with tape backing and aluminum coating at car supply stores, which are intended to be used in doors and engine compartments to reduce noise. The tape does seem to get worse over time due to it being attached directly to the heat source, but I’ve used it for a while.
Adrian had some other ideas way back: http://reprap.org/wiki/Mendel_heated_bed#Thermal_Insulation
Nophead started using only cardboard, if you read a bit down on this page. http://hydraraptor.blogspot.no/2013/10/mendel90-design-improvements.html