% thermarest filled with air
k1 = 0.024;
x1 = 6.35/100;  % thickness of thermarest = 6.35 cm

%thermarest filled with air with thin ice layer
% assuming thermarest has an area of 1 square meter
k2 = 2.18;
x2 = 1.2/1000;

U1 = k1/x1;
tmp = (x1-x2)/k1 + x2/k2;
U2 = 1/tmp;

fprintf('Conductances:\n');
fprintf('Thermarest alone: %g\n',U1);
fprintf('Thermarest with ice: %g\n',U2);

d = (U2-U1)/U1;  % calculate percentage change

fprintf('Percentage difference: %.2g%%\n',100*d);

% results
% Conductances:
% Thermarest alone: 0.377953
% Thermarest with ice: 0.385151
% Percentage difference: 1.9%