What is a word to describe a lifestyle of few possessions?

I think there is a word that exists, though it won't quite come to me, that describes the life of someone who purposely leads a sparse existence, materialistically, and has few, if any, possessions. The only word that comes to me is "monastic," but that's not quite right, and I'm thinking there exists a word that doesn't have any religious connotations. The right word could possibly, but not necessarily, indicate a nomadic quality, as well, or, at least, the quality of not being tied down to a particular location or domicile.

Example sentence:

Living in an easily-collapsed geodesic dome, and owning only a laptop, futon, table and a few sets of clothes, Ms. Hilgers' [single-word] lifestyle was envied by some and perplexing to others.

Spartan conveys the idea you are referring to:

simple and severe with no comfort:

• spartan living conditions; they lead a spartan life with very few comforts and no luxuries.

(Cambridge Dictionary)

I'd say it's minimalist.

Perhaps it does not dare make a virtue out of modernity and reinvent its interior in an honest minimalist style, so it serves up spadeloads of fake heritage instead.

The lean, minimalist design is refreshingly at odds with the usual run of touristy alpine decoration and furnishings featured at other ski resort hotels.

John McGowan's space may be a little larger but the minimalist style of small desk, computer station, neat cupboard space and obligatory plant is mirroring that of other employees.

How about austere?

3: markedly simple or unadorned · an austere office
_{from m-w.com}

Ascetic has some religious connotations but that doesn't necessarily preclude it from being usable if context doesn't include links to religion.

characterized by or suggesting the practice of severe self-discipline and abstention from all forms of indulgence, typically for religious reasons.

If you really want to drive home the lack of religious motivation, and you're okay with using two words, secular asceticism would probably fit the bill.