For any given substance, the heat capacity of a body is directly proportional to the amount of substance it contains (measured in terms of mass or moles or volume). Doubling the amount of substance in a body doubles its heat capacity, etc.
Conventional soft contacts can last up to a year; conventional rigid gas permeable (RGP) contact lenses can last even longer. Frequent or planned replacement contact lenses last one to several months. Disposable contacts last from one day (daily wear) to up to two weeks (extended wear).
Minimum prescription length. A contact lens prescription will only be valid for up to one year. Please state the law that says they can only be valid for one year. In the US, the FCLA states the MINIMUM prescription length is one year (except for extenuating, justified medical circumstances where it can be less).