function calculate() {
	hrsPerYr=365*24;
	kWhPrice=eval(18/100);
	kWhPriceNT=eval(7/100);
	
	var nrFields=document.forms["energieSparen"].elements.length-1;
	for (j=0;j<=nrFields;j++) {
		if (document.forms["energieSparen"].elements[j].type == 'hidden') {
			document.forms["energieSparen"].elements[j+1].value = 
				eval(document.forms["energieSparen"].elements[j].value);
			j++;
		}
	}
}

calculate();