 Elevators using hoist ropes, however, could only function effectively in low-rise buildings, and this limitation encouraged the introduction of the hydraulic elevator in 1870, even though early models contained dangerous design flaws.By 1876 these problems had been resolved, providing a solution for servicing the early skyscrapers.New environmental technologies in heating, lighting, ventilation and sanitation were also critical to creating taller buildings that were attractive to work in.