function calculateefficiency()
{

    var std_watt = $('#std_watt').val();
    var led_watt = $('#led_watt').val();
    /*var arrowIMG = new Element('img', {
        'src': '/extension/brumberg/design/brumberg_design/images/layout/content/double_arrow_green.gif'
    });*/
    var led_cost_per_item = 0;

    
    switch(Number(led_watt))
    {
        case 0:
            led_watt = 3.6;
            led_cost_per_item = 54.00;            
        break;
        case 1:
            led_watt = 2.8;
            led_cost_per_item = 67.00;
        break;
        case 2:
            led_watt = 5.0;
            led_cost_per_item = 84.00;
        break;
    }
    
    var pieces = $('#pieces').val();
    var time_per_day = $('#time_per_day').val();
    var days_per_year = $('#days_per_year').val();
    
    var costs = $('#costs').val();
    
    var std_cost_per_year = $('#std_cost_per_year');
    var led_cost_per_year = $('#led_cost_per_year');

    var std_single_costs = $('#std_single_costs');
    var led_single_costs = $('#led_single_costs');
    
    var amortisation_time = $('#amortisation_time');
    var saved_money = $('#saved_money');
    
    var std_co2 = $('#std_co2');
    var led_co2 = $('#led_co2');
    var kg_year = $('#kg_year');
    
    var std_jahresverbrauch = time_per_day*days_per_year*(std_watt/1000)*pieces;
    if(isNaN(std_jahresverbrauch) || $('#std_watt').val() == '' || $('#pieces').val() == '' || $('#time_per_day').val() == '' || $('#days_per_year').val() == '' || $('#costs').val() == '' )
    {
        $('#std_jahresverbrauch').text('');
        $('#led_jahresverbrauch').text('');
        
        $('#led_cost_per_year').text('');
        $('#std_cost_per_year').text('');
        $('#co2_led').text('');
        $('#co2_std').text('');
        $('#ersparnisproJahr').text('');
        $('#led_einmaligeAnschaffungskosten').text('');
        ('#Amortisierungsdauer').text('');
        $('#co2_redu').text('');
        $('#co2_redu_percent').text('');
        $('#led_anschaffungskosten').text('');
    }else{
        
        $('#led_anschaffungskosten').text(led_cost_per_item.toFixed(2));
        $('#std_jahresverbrauch').text(std_jahresverbrauch.toFixed(2));
        var led_jahresverbrauch = time_per_day*days_per_year*(led_watt/1000)*pieces;
        $('#led_jahresverbrauch').text(led_jahresverbrauch.toFixed(2));
    
        var led_costs = (costs/100)*led_jahresverbrauch;
        $('#led_cost_per_year').html('<img src="/extension/brumberg/design/brumberg_design/images/layout/content/double_arrow_black.gif" />'+' '+led_costs.toFixed(2));
        var std_costs = (costs/100)*std_jahresverbrauch;
        $('#std_cost_per_year').html('<img src="/extension/brumberg/design/brumberg_design/images/layout/content/double_arrow_black.gif" />'+' '+std_costs.toFixed(2));
        
        var ersparnisProJahr = std_costs-led_costs;
        $('#ersparnisproJahr').html('<img src="/extension/brumberg/design/brumberg_design/images/layout/content/double_arrow_black.gif" />'+' '+ersparnisProJahr.toFixed(2));
        // CONST:
        
            var std_cost_per_item = 11;//$('#std_anschaffungskosten').val();
            $('#std_anschaffungskosten').text(std_cost_per_item.toFixed(2));
            
            var std_jahresbesch_menge = pieces/(2000/(time_per_day*days_per_year));
            $('#std_jahresbesch_menge').text(std_jahresbesch_menge.toFixed(2));
            
            var std_yearly_single_costs = std_jahresbesch_menge*std_cost_per_item;
            var led_single_costs = pieces*led_cost_per_item;
            $('#led_einmaligeAnschaffungskosten').text(led_single_costs.toFixed(2));
            $('#std_yearlycosts').text(std_yearly_single_costs.toFixed(2));
        // END    
        
        var amor_time = led_single_costs/((std_costs-led_costs)+std_yearly_single_costs);
        
        var std_co2_per_year = std_jahresverbrauch*0.42;
        var led_co2_per_year = led_jahresverbrauch*0.42;
    
        $('#co2_std').text(std_co2_per_year.toFixed(2));
        $('#co2_led').text(led_co2_per_year.toFixed(2));
    
        var co2_reduzierung = std_co2_per_year - led_co2_per_year;
        var co2_reduzierung_percent = ((100/std_co2_per_year*co2_reduzierung).toFixed(2));
        
        $('#co2_redu').html('<img src="/extension/brumberg/design/brumberg_design/images/layout/content/double_arrow_black.gif" />'+' '+co2_reduzierung.toFixed(2)+' / ');
        $('#co2_redu_percent').html('<img src="/extension/brumberg/design/brumberg_design/images/layout/content/double_arrow_black.gif" />'+' '+co2_reduzierung_percent + ' %');
        
        $('#Amortisierungsdauer').text(amor_time.toFixed(5));
        /*
            Variables:
            
            amor_time - Amortisierungszeit
            led_costs - LED Energiekosten / Jahr
            std_costs - LED Energiekosten / Jahr
            std_jahresanschaffungskosten - Jahresanschaffungskosten
            std_jahresbesch_menge - Jahresbeschaffungsmenge
            led_single_costs - Einmalige Anschaffungskosten
            std_co2_per_year - CO2 Ausstoß pro Jahr (normale Birne)
            led_co2_per_year - CO2 Ausstoß pro Jahr (LED)
            
            co2_reduzierung - co2 Austoßreduzierung
            co2_reduizierung_percent - co2 Austoßreduzierung (%)
        
        */
    }
}