Error in FUN(newX[, i], ...) : argument "Iclo" is missing, with no default
This is the answer:

pmv1 = function(H,pa,Ta,fcl,Tr,Iclo,M){
  Tcl = (35.7 - 0.0275*H + 0.155*Iclo * 
           (H - 0.31*(57.4 - 0.07*H - pa) - 
              0.42*(H - 58) - 0.0017*M*(58.7 - pa) - 
              0.0014*M*(34 - Ta)))

  hc=(2.4*(Tcl - Ta))
  dT= (Tr - 22)

  PMV= (4 + (0.303 *exp(-.036*H) + 0.0275)* 
          (6.57 + 0.46*H +.31*pa + 0.0017*H*pa + 0.0014*H*Ta - 4.13 *fcl 
           *((1 + 0.01*dT) * (Tcl - Tr))-fcl *(Tcl - Ta)))
  return((PMV-min(PMV))*3/(max(PMV)-min(PMV))-0)
}

d &lt;- 7

n &lt;- 250

set.seed(0)

X1 &lt;- optimumLHS(n, d)
X1 &lt;- data.frame(X1)

#colnames(X1) &lt;- c("H","pa","Ta","fcl","Tr","Iclo","M")
new &lt;- pmv1(X1[,1],X1[,2],X1[,3],X1[,4],X1[,5],X1[,6],X1[,7])


This would do the job.