function setInstallationType($installationType) {
		if ($installationType == (self::INSTALLATION_TYPE_WINDOW or self::INSTALLATION_TYPE_DOOR)) {
			$this->installationType = $installationType;
		} else {
			throw new Exception(sprintf("Invalid installationtype. Allowed values: '%s', '%s'",self::INSTALLATION_TYPE_WINDOW, self::INSTALLATION_TYPE_DOOR));
		}
		
	}