Residence is based on number of days spent in a country, and some countries have slightly different rules. If you live in Ireland, I would guess that you are Irish resident, however, you can be resident in more than one country at a time.
As a rule of thumb, if you are in a country for 183 days or more in a year you are likely to be resident there, however, for example if you more than 91 days for several years in the UK, you may be treated as resident there also.
If you are concerned about your residence situation, you should get professional advice.