We use a 3 stage insulation system in all of our conversions. Stage 1, Thin, flexible, easy to install, aluminium bubble insulation membrane which acts by trapping air within the bubble structure while creating low emissivity air spaces from foil-faced outer layers, enhancing overall thermal capabilities. . Stage 2, eco-friendly recycled plastic bottle insulation provides 0.040 W/mK thermal conductivity and can offer you acoustic reduction of up to 40dB. Installing just one pack takes 800 plastic bottles out of circulation.  Stage 3, using the same components as in stage 1 creating an overall amazing thermal barrier for all climates