The author describes the house and its technological functions in terms of being "alive." This is an example of personification. However, given that metaphor is a figure of speech that is used to describe one thing as if it is the same as another unrelated thing, we can say...
The author describes the house and its technological functions in terms of being "alive." This is an example of personification. However, given that metaphor is a figure of speech that is used to describe one thing as if it is the same as another unrelated thing, we can say that the house (and/or the advanced technology that it makes use of) is a metaphor for living beings. The irony then is that, of course, the house and its machines are not alive. Bradbury uses this irony to show a stark future when humans have allowed technology to take over their lives. While technology can offer convenience and comfort to human lives, it can become so active (and humans so passive) that it becomes more alive while humans, continuing to do less and less for themselves, become more dead, so to speak. (Conversely, had humans been in they story, they may have been described as metaphors for machines.)
In the story, humans have used another type of technology (atomic weapons) to destroy themselves, making them literally dead. And this leaves only the scarred remains of the house and other seemingly "alive" machines. This is an interesting use of metaphor and personification wherein the house (a non-living thing) is described as living but only to show how it is, in fact, not living. In this sense, it is a kind of metafiction: a metaphor that calls attention to the fact that it is not true. As the house is dying, it is dramatic but also unbelievable in the ways that the voices call out to the humans to escape; thus revealing that the house is unaware that the humans are gone. The house is unconscious, just a machine:
And the voices wailed Fire, fire, run, run, like a tragic nursery rhyme, a dozen voices, high, low, like children dying in a forest, alone, alone. And the voices fading as the wires popped their sheathings like hot chestnuts. One, two, three, four, five voices died.