Is there a difference in meaning between "aggregate" and "aggregated"?

Solution 1:

"Aggregated" is the past tense construction of the verb "to aggregate". In contrast, "aggregate" is an adjective ("aggregated is not an adjective).

The company aggregated sales figures to check expectations. (verb)
The aggregate sales of the company exceeded expectations. (adjective)

For your phrase:

The aggregate consumption of oil consumed to heat households in the country is more than three times the next largest national consumption.

(To be fair, the use of the past tense verb as an adjective is not strictly wrong. In English, we can take nearly any verb and apply it as an adjective: "an exploded bomb", "a convinced electorate", "the totaled figures". However, because there is a specifically defined adjective for this particular word, I would suggest sticking with the completely correct "aggregate".)