Building Energy Ratings in Co. Mayo
37,837 certificates · median 209 kWh/m²/yr · rank 46 of 52 counties on the share rated B3 or better
Half of the dwellings rated in Co. Mayo use more than 209 kWh/m²/yr.
The national median is 178 kWh/m²/yr. 29.3% of the certificates on the 2009 scale are B3 or better; 27.0% are E, F or G.
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Ratings
2009 scale, A1 to E2 — 31,179 certificates
| Rating | Certificates | Share |
|---|---|---|
| A1 | 544 | 1.7% |
| A2 | 2,038 | 6.5% |
| A3 | 1,621 | 5.2% |
| B1 | 1,032 | 3.3% |
| B2 | 1,433 | 4.6% |
| B3 | 2,470 | 7.9% |
| C1 | 3,145 | 10.1% |
| C2 | 4,069 | 13.1% |
| C3 | 4,307 | 13.8% |
| D1 | 3,858 | 12.4% |
| D2 | 3,369 | 10.8% |
| E1 | 1,761 | 5.6% |
| E2 | 1,532 | 4.9% |
2026 scale, A0 to E — 1,596 certificates
| Rating | Certificates | Share |
|---|---|---|
| A0 | 138 | 8.6% |
| A | 229 | 14.3% |
| B | 531 | 33.3% |
| C | 471 | 29.5% |
| D | 158 | 9.9% |
| E | 69 | 4.3% |
F and G — the same on both scales
| Rating | Certificates | Share of all certificates |
|---|---|---|
| F | 1,775 | 4.7% |
| G | 3,287 | 8.7% |
⚠️ The two scales are shown apart on purpose: adding a « B » from the 2026 scale to « B1+B2+B3 » from the 2009 scale would produce a number that exists nowhere. F and G belong to both, so they are counted in neither distribution and shown on their own. How the two scales compare.
What the certificates measure
| Certificates | 37,837 |
| Median energy use | 209 kWh/m²/yr |
| Median CO₂ | 50.1 kg CO₂/m²/yr |
| Median floor area | 116 m² |
| Median wall U-value | 0.38 W/m²K |
| Median roof U-value | 0.23 W/m²K |
| Median floor U-value | 0.44 W/m²K |
| Median window U-value | 2.70 W/m²K |
| Median heating system efficiency | 86% |
| Certificates with solar PV | 546 (1.4%) |
| Median renewable energy ratio | 0.00 |
| National median energy use | 178 kWh/m²/yr |
By period of construction
| Built | Certificates | Median kWh/m²/yr | Median wall U-value |
|---|---|---|---|
| before 1900 | 677 | 387 | 1.53 |
| 1900–1944 | 4,839 | 367 | 1.41 |
| 1945–1969 | 3,161 | 316 | 0.95 |
| 1970–1979 | 3,589 | 261 | 0.57 |
| 1980–1990 | 4,526 | 235 | 0.41 |
| 1991–1999 | 5,439 | 209 | 0.43 |
| 2000–2004 | 5,997 | 193 | 0.54 |
| 2005–2009 | 6,102 | 161 | 0.37 |
| 2010–2018 | 1,237 | 64 | 0.20 |
| 2019 or later | 2,270 | 40 | 0.17 |
Periods with fewer than 11 certificates are not shown separately.
By dwelling type
| Type | Certificates | Median kWh/m²/yr | Median floor area (m²) |
|---|---|---|---|
| Detached house | 21,672 | — | — |
| Semi-detached house | 7,628 | — | — |
| Mid-terrace house | 2,547 | — | — |
| End of terrace house | 1,652 | — | — |
| Top-floor apartment | 1,297 | — | — |
| House | 1,245 | — | — |
| Ground-floor apartment | 894 | — | — |
| Mid-floor apartment | 663 | — | — |
| Maisonette | 184 | — | — |
| Apartment | 52 | — | — |
Main space heating fuel
| Fuel | Certificates | Share | Median kWh/m²/yr |
|---|---|---|---|
| Heating Oil | 25,302 | 66.9% | — |
| Electricity | 8,234 | 21.8% | — |
| Solid Multi-Fuel | 2,018 | 5.3% | — |
| Mains Gas | 973 | 2.6% | — |
| Bulk LPG (propane or butane) | 730 | 1.9% | — |
| Sod Peat | 122 | 0.3% | — |
| Manufactured Smokeless Fuel | 99 | 0.3% | — |
| Bottled LPG | 79 | 0.2% | — |
| Wood Pellets (bulk supply for | 77 | 0.2% | — |
| House Coal | 57 | 0.2% | — |
One certificate is one assessment of one dwelling, not one dwelling: a home rated twice appears twice. How this is counted.