startElement.setAttribute("uncertainty", "1.0");
startElement.setText(idf.format(event.getStart()));
Element endElement = new Element("endTime", meterNS);
endElement.setAttribute("uncertainty", "1.0");
endElement.setText(idf.format(event.getEnd()));
Element quantityElement = new Element("quantity", meterNS);
quantityElement.setAttribute("uncertainty", "0.001");
quantityElement.setAttribute("unit", "kW h");
quantityElement.setText(event.getQuantity() + "");