Is it a good idea to include a value column (e.g. from measurements) in an index?
You have a time series (measurements) organized by id (clustered index). I am yet to see a single case where using id as clustered key for time series makes sense. All queries will ask for date ranges. Organize by time:

CREATE TABLE measurements
(
    id bigint IDENTITY,
    parameter_id int NOT NULL,
    measuretime datetime NOT NULL,
    value float NOT NULL,
    PRIMARY KEY NONCLUSTERED (id ASC)
);

CREATE CLUSTERED INDEX cdx_measurements ON measurements(measuretime);


Yes, lookup by id will take two reads instead of one. Who cares, id is looked up in singletons. Is a trade off.