Is a C3 good or bad?
A C3 home is among the more efficient in the country, with relatively low heating demand and running costs.
How to improve beyond C3
Homes at this level are already efficient; small gains come from controls, draught-proofing or solar PV.
The typical measures are grant-aided by SEAI. See the grants, or estimate your own home to get a tailored list.
See what your own home is likely rated
Four questions, real data, the grants that apply.