37 Building construction; repair of heating, ventilating and air conditioning units; repair of industrial furnaces; cleaning of building interiors; installation and repair of machines and production installations, in particular industrial washing and painting installations; servicing of filtering installations; installation of electrical wiring and fittings; cleaning of industrial installations, steelworks and power stations; reconditioning machines and motors and engines that are worn out or partially destroyed; assembly and disassembly of machines and installations; installation, repair and maintenance of data technology installations (hardware); assembly of air conveying apparatus; demolition, blasting and earth-moving operations; providing of services in the environmental sector, namely, remediation of contaminated sites by cleaning