Trelyn Lane Pengam, Caerphilly
15 addresses across 2 postcodes (NP12), about 150 m long, classed as a local road. USRN 47503561.
- Sales: 7 recorded sales since 1995; in 2021 the median was £80,000 across 1 sale.
- Prices and rents: A typical home in Caerphilly cost £198,545 in August 2026 (+4.4% on a year); private rents averaged £752 a month.
- Energy: 9 homes have an energy certificate (C: 2, D: 3, E: 4).
- Flood: No postcode centre on the street is in flood zone 2 or 3.
- Recorded floods: No recorded flood covers the centre of any of its postcodes.
- Coal mining: It is in a coalfield, in a low risk area.
- Landfill: 2 historic landfill sites within 500 m (0.3 miles) of its postcodes; the nearest, Rear Of William Street, is 140 m away.
- Radon: Up to 5 to 10% of homes in the 1 km squares around it are estimated to be at or above the radon Action Level.
- Energy projects: 1 renewable energy project nearby is planned or being built; the nearest, Trecelyn Wind Farm, is 5 km (3.1 miles) away.
- Traffic: The busiest counted road within 500 m (0.3 miles), the A469, carries 14,100 motor vehicles a day on average (2025).
- Council tax: Most homes around it are in council tax band B; Band D in Caerphilly costs £2,083 a year in 2026-27.
- Broadband: Gigabit broadband is available to 100% of premises.
- Transport: The nearest railway station is Pengam, about 910 m (0.6 miles) away in a straight line.
- Green space: The nearest park or garden, Parc Coetir Bargod, is about 860 m (0.5 miles) away.
- Air: Background air pollution in 2024 was 8.8 µg/m³ of nitrogen dioxide and 5.8 of PM2.5, within UK legal limits.
- Height: Its addresses are 122 to 132 m above sea level.
- Noise: 5 of its 15 addresses are modelled at 55 dB or more from road traffic.
- Doctors: The nearest GP surgery is Pengam Health Centre, about 360 m away, with 2 practices within 1.6 km (1 mile).
- People: About 370 people lived in the census areas around it in 2021; 85% of households owned their home and 26% of adults held a degree or other higher qualification.
- Crime: 78 crimes were recorded within 250 m between September 2025 and August 2026, most often violence and sexual offences.
- Road safety: 1 collision in which someone was hurt was reported on and around it in 2021 to 2025, and it was serious.
£9.99 The Street Dossier Full Report for a home on Trelyn Lane: its own records, questions to ask the seller and everything on this page, in one PDF. Choose the home
House sales on this street
| Year | Sales | Median price | Lowest | Highest |
|---|---|---|---|---|
| 2021 | 1 | £80,000 | £80,000 | £80,000 |
| 2019 | 1 | £125,000 | £125,000 | £125,000 |
| 2016 | 1 | £242,000 | £242,000 | £242,000 |
| 2010 | 1 | £121,000 | £121,000 | £121,000 |
| 2006 | 1 | £250,000 | £250,000 | £250,000 |
| 2005 | 1 | £76,000 | £76,000 | £76,000 |
| 1997 | 1 | £50,000 | £50,000 | £50,000 |
| Date | Address | Type | Price | Notes |
|---|---|---|---|---|
| 25 Sep 2019 | 2 NP12 3XU | Terraced | £125,000 | |
| 14 May 2010 | 3 NP12 3XU | Terraced | £121,000 | |
| 1 Jul 2005 | 4 NP12 3XU | Terraced | £76,000 | |
| 28 Apr 2021 | 8 NP12 3XU | Semi-detached | £80,000 | |
| 15 Jul 2016 | DARREN FELYN NP12 3XU | Semi-detached | £242,000 | |
| 20 Oct 2006 | DARREN FELYN NP12 3XU | Detached | £250,000 | |
| 28 Oct 1997 | DARREN FELYN NP12 3XU | Detached | £50,000 |
House prices and rents in Caerphilly
A typical home in Caerphilly cost £198,545 in August 2026, 4.4% more than a year before. That is 25% more than five years earlier and 70% more than ten years earlier.
| Home | Typical price, Aug 2026 |
|---|---|
| Detached | £313,999 |
| Semi-detached | £202,994 |
| Terraced | £169,311 |
| Flat or maisonette | £107,649 |
| Bought by a first-time buyer | £180,385 |
Private renters in Caerphilly paid £752 a month on average in September 2026, 7.1% more than a year before. That is 42% more than five years earlier.
| Home | Average rent a month, Sep 2026 |
|---|---|
| One bedroom | £554 |
| Two bedrooms | £693 |
| Three bedrooms | £781 |
| Four or more bedrooms | £1,101 |
Energy performance certificates
9 homes with a current certificate; median floor area 101 m². Most common: House, mid-terrace (3); House, semi-detached (3); House, end-terrace (2). Built: 1900-1929 (7); before 1900 (1); 1983-1990 (1). Tenure at assessment: owner-occupied (6); rented (private) (2).
Each home's certificates and sales (9 addresses)
Gas and electricity use
Homes with gas used 11,246 kWh of it on average in 2024, about the same as the district, and 2,259 kWh of electricity, 23% less than the district's 2,947 kWh. There are gas meters for about 96% of the homes.
| Postcode | Electricity meters | Typical electricity | Gas meters | Typical gas |
|---|---|---|---|---|
| NP12 3XU | 14 | 1,832 kWh | 12 | 9,225 kWh |
| NP12 3XT | 13 | 1,322 kWh | 14 | 11,259 kWh |
These are all the homes on each postcode, whatever their size and however many live in them, so they show the kind of homes and heating here rather than what any one home uses. The typical figure is the median: half the homes used less. The district is NP12.
Council tax
What each band costs in Caerphilly in 2026-27: Band D £2,083 a year on average, including the police and community council charges.
| A | B | C | D | E | F | G | H | I |
|---|---|---|---|---|---|---|---|---|
| £1,389 | £1,620 | £1,851 | £2,083 | £2,546 | £3,009 | £3,471 | £4,166 | £4,860 |
Homes by band in the neighbourhood around this street: most are in band B (48% of about 520 homes).
Planning and heritage
- Conservation area: no postcode centre in this street's postcodes is in one.
- Listed buildings on or by this street: none.
- Article 4 directions, tree preservation orders and green belt: Wales has no national record of these; the council's planning department holds them.
Energy projects nearby
3 energy projects near the street's postcodes, 1 of them not yet operating.
| Project | Kind | Size | Stage | Distance |
|---|---|---|---|---|
| Gelliargwellt Uchaf Farm AD Caerphilly 11/0224/FULL | Anaerobic digestion | 1.4 MW | Operational Feb 2016 | 3.1 km (1.9 miles) |
| Oakdale Business Park Caerphilly 11/0552/FULL | Wind 2 turbines | 4 MW | Operational Dec 2013 | 4.5 km (2.8 miles) |
| Trecelyn Wind Farm Welsh Government (NSIP) DNS CAS-02114-J9X4S6 | Wind 4 turbines, 145 m tall | 20 MW | Planning application made Jun 2024 | 5 km (3.1 miles) |
Planned projects can change or not go ahead; search the planning authority's applications by the reference shown for the plans, conditions and any objections. Construction brings traffic for some months; once built, solar farms and batteries are usually quiet, while turbines and waste plants can be seen or heard further away.
Roadworks
Street works permits come from the Department for Transport's Street Manager, which covers England only.
Flood risk
Rivers, the sea or surface water: of the 30 address points in this street's postcodes, 1 at high risk, 0 at medium risk and 5 at low risk. Each counts once, at the higher of its rivers-and-sea and surface-water risk.
Rivers and the sea alone: 1 at high risk, 0 at medium risk and 0 at low risk. Surface water and small watercourses alone: 1 at high risk, 0 at medium risk and 5 at low risk.
High: 3.3% (1 in 30) or more chance of flooding a year. Medium: 1% to 3.3%. Low: 0.1% to 1%. The map allows for flood defences. Address points are every property record (UPRN) in the postcode, each counted if it is in an area or within 5 m of one (the maps stop at building walls); a few are not homes, such as garages, business units or caravan pitches. Counts cover whole postcodes, which can include other streets.
Flood zone for planning: no postcode centre on this street is in flood zone 2 or 3. Welsh zones include an allowance for climate change.
| Postcode | Planning zone | Addresses at high / medium / low risk |
|---|---|---|
| NP12 3XU | not in 2 or 3 | 1 / 0 / 2 |
| NP12 3XT | not in 2 or 3 | 0 / 0 / 3 |
Recorded floods
No recorded flood covers the centre of any of this street's postcodes.
Recorded floods are where floodwater was seen or surveyed after a flood. Many floods were never mapped, an outline over a postcode's centre does not mean every home in it flooded, and homes outside one may have. Ask the seller whether the home itself has flooded.
Coastal erosion
No projected coastal erosion zone is within 1 km (0.6 miles) of the street's postcodes.
Storm overflows
No storm overflow outlet is within 1 km (0.6 miles) of the street's postcodes in this record, which covers the overflows reported to the Environment Agency: most of Wales's are reported to Natural Resources Wales instead.
Coal mining
2 of the street's 2 postcodes are in a coalfield, in a low risk area: coal was mined in the area, but no workings shallow enough to matter for building are recorded.
Conveyancers usually still order a coal mining search (CON29M) for a home in a coalfield.
Radon
The highest radon potential in the 1 km squares around the street's postcodes is 5 to 10%: up to that share of homes there is estimated to be at or above the Action Level of 200 becquerels per cubic metre. At least part of that area is a radon Affected Area, where 1% or more of homes are.
Radon is a natural radioactive gas from the ground that can build up indoors; long exposure raises the risk of lung cancer. A three-month test with two small detectors is the only way to know a home's level, and a high level can usually be brought down with a sump or better ventilation. Homes built here in recent decades should have radon protection under the building regulations (basic protection from 3%, full protection from 10%). UKHSA sells a radon report for a single address from its detailed map at ukradon.org.
Historic landfill
2 historic landfill sites are within 500 m (0.3 miles) of the street's postcodes, the nearest 140 m away.
| Site | Waste went in | Waste | Distance |
|---|---|---|---|
| Rear Of William Street Tir-Y-Berth | 1988 to 1989 | Inert | 140 m |
| Glan Yr Afon Commercial Street, Blackwood | Not recorded | Industrial, household | 200 m |
Closed tips can give off gas (methane and carbon dioxide) and leak into the ground for years. An environmental search, which conveyancers usually order, looks at landfill and contaminated land around the home; the council keeps a register of land it has found to be contaminated.
Height above sea level
The street's 15 addresses are between 122 m and 132 m above sea level (129 m on average); the ground rises about 10 m from the lowest to the highest.
Broadband
| Postcode | Superfast (30 Mbit/s+) | Ultrafast (300 Mbit/s+) | Gigabit | Below 10 Mbit/s |
|---|---|---|---|---|
| NP12 3XT | 100% | 100% | 100% | 0% |
| NP12 3XU | 100% | 100% | 100% | 0% |
Getting around
| Nearest | Distance | |
|---|---|---|
| Railway stations | Pengam 214,000 journeys in 2024–25 | 910 m (0.6 miles) |
| Hengoed 129,000 journeys in 2024–25 | 1.7 km (1.1 miles) | |
| Gilfach Fargoed 5,140 journeys in 2024–25 | 2.4 km (1.5 miles) | |
| Bus stops | 8 stops within 400 m (0.2 miles), 23 within 800 m (0.5 miles); nearest Gwent Court Fleur-de-lis | 140 m |
| Bus or coach station | Blackwood Bus Station Stand 1 | 2 km (1.2 miles) |
| EV charging points | 1 within 1.6 km (1 mile); nearest Connected Kerb Charging Stations | 850 m (0.5 miles) |
| Airport with scheduled flights | Cardiff International Airport CWL | 30.8 km (19 miles) |
Local services
| Nearest | Distance | |
|---|---|---|
| GP surgeries | 2 practices within 1.6 km (1 mile); nearest Pengam Health Centre | 360 m |
| Pharmacies | 2 pharmacies within 1.6 km (1 mile); nearest Vida Rogers LTD | 150 m |
| NHS dentists | Dental Surgery | 2.1 km (1.3 miles) |
| Hospital | Ysbyty Ystrad Fawr | 3.5 km (2.2 miles) |
| Police station | Blackwood Police Station | 2.2 km (1.4 miles) |
| Cash machines | Tesco Bank ATM | 1.2 km (0.8 miles) |
Parks and green space
| Nearest | Distance | |
|---|---|---|
| Park or garden | Parc Coetir Bargod 96 ha | 860 m (0.5 miles) |
| Play area | 6 within 800 m (0.5 miles); nearest Unnamed 360 m² | 230 m |
| Playing field | 3 within 800 m (0.5 miles); nearest Unnamed 1.7 ha | 360 m |
| Allotments | 7 within 800 m (0.5 miles); nearest Unnamed 6,110 m² | 160 m |
Landmarks
The nearest historic landmark is Twyn Castell, a scheduled monument, 1.8 km (1.1 miles) west. 3 listed buildings are within 1 km (0.6 miles).
| Name | What it is | From the middle of the street |
|---|---|---|
| Twyn Castell | Scheduled monument | 1.8 km (1.1 miles) west |
| Maes Manor Hotel | Registered park or garden, Grade II | 2.9 km (1.8 miles) north-east |
| Name | What it is | From the middle of the street |
|---|---|---|
| Tir-y-bont Wood | Wood | 1.1 km (0.7 miles) north |
| Gwerthonor-isaf Wood | Wood | 1.4 km (0.9 miles) north-west |
| Coed Duon | Wood | 1.6 km (1 mile) east |
| Coed Ty'n-y-pwll | Wood | 1.8 km (1.1 miles) north-east |
| Cwm Gelli | Valley | 2.6 km (1.6 miles) north-east |
| Nant-y-draenog Reservoir | Lake or reservoir | 4.7 km (2.9 miles) south-east |
Air quality
| Pollutant | Here | UK limit | WHO guideline |
|---|---|---|---|
| Nitrogen dioxide (NO2) | 8.8 | 40 | 10 |
| Fine particles (PM2.5) | 5.8 | 20 | 5 |
| Particles (PM10) | 9.0 | 40 | 15 |
All three are within the UK legal limits; PM2.5 is above the WHO guideline, as in most towns and cities.
Road and rail noise
| Level | Road traffic | Railways |
|---|---|---|
| 55 to 59 | 5 | 0 |
| Under 55 | 10 | 15 |
5 of the street's 15 addresses are modelled at 55 dB or more from road traffic, above the WHO guidelines.
Climate, daylight and earthquakes
Monthly temperatures and rainfall, sunrise and sunset through the year, and earthquakes recorded nearby since 1970 are much the same across the area, so they are worked out once for Caerphilly: see them on the Caerphilly page.
Nearest schools
| School | Phase | Ages | Distance | Inspection | Exam results |
|---|---|---|---|---|---|
| Tiryberth Primary English medium | Primary | 3–11 | 330 m | Estyn reports · My Local School | Not published in Wales |
| Ysgol Gyfun Cwm Rhymni Welsh medium | Secondary | 11–19 | 640 m (0.4 miles) | Estyn reports · My Local School | Not published in Wales |
| Pengam Primary English medium | Primary | 3–11 | 660 m (0.4 miles) | Estyn reports · My Local School | Not published in Wales |
| Ysgol Gymraeg Trelyn Welsh medium | Primary | 3–11 | 660 m (0.4 miles) | Estyn reports · My Local School | Not published in Wales |
| Fleur-de-Lys Primary English medium | Primary | 3–11 | 670 m (0.4 miles) | Estyn reports · My Local School | Not published in Wales |
| Derwendeg Primary School English medium | Primary | 3–11 | 950 m (0.6 miles) | Estyn reports · My Local School | Not published in Wales |
| The Lewis School English medium | Secondary | 11–19 | 1.1 km (0.7 miles) | Estyn reports · My Local School | Not published in Wales |
| Cefn Fforest Primary English medium | Primary | 3–11 | 1.3 km (0.8 miles) | Estyn reports · My Local School | Not published in Wales |
| Glyn-Gaer Primary School English medium | Primary | 3–11 | 1.5 km (0.9 miles) | Estyn reports · My Local School | Not published in Wales |
| Blackwood Primary English medium | Primary | 3–11 | 1.5 km (1 mile) | Estyn reports · My Local School | Not published in Wales |
| Hengoed Primary English medium | Primary | 3–11 | 1.6 km (1 mile) | Estyn reports · My Local School | Not published in Wales |
| Blackwood Comprehensive School English medium | Secondary | 11–16 | 1.6 km (1 mile) | Estyn reports · My Local School | Not published in Wales |
Exam results are from the Department for Education's school performance tables (Explore Education Statistics, Open Government Licence), for all pupils at each school. The middle school in England had 63% at the expected standard at the end of primary school (2025), Attainment 8 of 46.0 at GCSE (2026) and an A level average of C+ (2025). Attainment 8 adds up a pupil's grades in eight GCSEs, with English and maths counted twice (90 is the most), averaged over the school's pupils. Progress 8 compares pupils with others who had the same results at the end of primary school; it is not published for GCSEs in 2025 and 2026, as those pupils sat no primary tests during the pandemic. Small year groups swing from year to year, and figures for very small ones are withheld. Wales publishes no school results tables.
Nurseries and childcare
Ofsted registers childcare in England only. In Wales, nurseries, playgroups and childminders are registered and inspected by Care Inspectorate Wales, whose directory of services lists them with their reports.
Food hygiene ratings nearby
| Business | Type | Distance | Rating | Rated |
|---|---|---|---|---|
| Keith's Fruit & Veg NP12 3UB | Retailers - other | 100 m | 4 Good | 4 Jun 2025 |
| Wu's Garden NP12 3UB | Takeaway/sandwich shop | 120 m | 5 Very good | 23 Mar 2026 |
| Fleur De Lis RFC NP12 3UD | Pub/bar/nightclub | 120 m | 3 Generally satisfactory | 25 Jan 2025 |
| Secrets Bakehouse NP12 3UB | Other catering premises | 130 m | Awaiting inspection | |
| Ty Afon Residential Home NP12 3XS | Hospitals/Childcare/Caring Premises | 130 m | 5 Very good | 24 Nov 2023 |
| Premier NP12 3UD | Retailers - other | 130 m | 3 Generally satisfactory | 30 Oct 2025 |
| Marmaris Kebab House NP12 3UB | Takeaway/sandwich shop | 130 m | 4 Good | 17 Jul 2026 |
| Coffee @ Style NP12 3UB | Restaurant/Cafe/Canteen | 140 m | 1 Major improvement necessary | 11 Sep 2026 |
| Valley Tavern Limited NP12 3UD | Pub/bar/nightclub | 150 m | 5 Very good | 30 Aug 2024 |
| Vida Rogers Ltd NP12 3UD | Retailers - other | 150 m | Exempt | |
| Fleur De Lis Post Office NP12 3UE | Retailers - other | 150 m | Exempt | |
| New City 2025 Limited NP12 3UD | Takeaway/sandwich shop | 200 m | 3 Generally satisfactory | 13 Aug 2026 |
| Cylch Meithrin Blodau Bach NP12 3AB | Hospitals/Childcare/Caring Premises | 220 m | 3 Generally satisfactory | 17 Mar 2025 |
| Tir-Y-Berth Primary Canteen CF82 8AU | School/college/university | 320 m | 5 Very good | 30 Sep 2024 |
| Greenfields Nursery Tir-Y-Berth@ CF82 8AU | Hospitals/Childcare/Caring Premises | 320 m | 5 Very good | 14 Apr 2026 |
Crime within 250 m
| Category | Crimes |
|---|---|
| Violence and sexual offences | 29 |
| Anti-social behaviour | 14 |
| Public order | 11 |
| Vehicle crime | 8 |
| Criminal damage and arson | 6 |
| Shoplifting | 6 |
| Burglary | 2 |
| Possession of weapons | 1 |
| Other crime | 1 |
Most of these are attached to: On or near High Street (30); On or near Grey Crescent (8); On or near Ivor Street (8); On or near Trelyn Lane (6); On or near Duffryn Street (4).
Road safety
1 collision in which someone was hurt was reported on and around the street in 2021 to 2025: 0 fatal, 1 serious and 0 slight, in which 1 person was seriously hurt. 100% happened in the dark. Most were on roads with a 30 mph limit.
| Year | Collisions | Fatal or serious |
|---|---|---|
| 2021 | 1 | 1 |
| 2022 | 0 | 0 |
| 2023 | 0 | 0 |
| 2024 | 0 | 0 |
| 2025 | 0 | 0 |
| Date | Severity | Who was hurt | Road | Conditions |
|---|---|---|---|---|
| 15 Sep 2021 23:40 | Serious | 3 people | B4252, 30 mph | Dark, street lights on |
Only collisions in which someone was hurt and which the police were told about are here: damage-only collisions and near misses are not, and some injuries are never reported. Positions are recorded by the police, usually to within a few metres. Each year's figures are published the following September.
Traffic on nearby roads
The busiest counted road within 500 m (0.3 miles) is the A469 between A472 and B4254, with 14,100 motor vehicles a day on average in 2025, 460 m (0.3 miles) from the street's postcodes.
| Road | Between | Vehicles a day | Lorries | Ten years before | Distance |
|---|---|---|---|---|---|
| A4049 | A472 to Pencam | 7,320 counted 2025 | 2% | +4% since 2015 | 410 m (0.3 miles) |
| A469 | A472 to B4254 | 14,100 estimated | 2% | 460 m (0.3 miles) | |
| A469 | A472 to B4254 | 13,933 estimated; counted 2023 | 2% | +39% since 2014 | 460 m (0.3 miles) |
Each figure is the annual average daily flow: the motor vehicles passing the count point, both ways, on an average day of the year. A point is counted by hand on a weekday every few years and estimated from the trend on similar roads in between. Lorries are heavy goods vehicles, as a share of all motor vehicles.
People and work
Who lives here
| Around this street | Wales | |
|---|---|---|
| Median age | 53 | 43 |
| Children under 15 | 10% | 17% |
| Aged 65 and over | 33% | 21% |
Homes
| Around this street | Wales | |
|---|---|---|
| Owned (outright or with a mortgage) | 85% | 66% |
| Owned outright | 51% | 38% |
| Shared ownership | 0% | under 1% |
| Social rented | 9% | 17% |
| Private rented | 7% | 17% |
Work and commuting
| Around this street | Wales | |
|---|---|---|
| Adults (16 and over) in work | 45% | 54% |
| Unemployment (of those working or looking for work) | 5% | 6% |
| Retired (of adults) | 36% | 25% |
| Long-term sick or disabled (of adults) | 9% | 6% |
| Work mainly from home (of those in work) | 22% | 26% |
| Travel to work by car or van | 71% | 61% |
| By train, Underground, metro or tram | 2% | under 1% |
| By any public transport, including bus | 2% | 3% |
| On foot or by bicycle | 5% | 8% |
| Work within 10 km (6 miles) of home (of those who travel to work) | 54% | 60% |
| Work 30 km (19 miles) or more away | 10% | 10% |
Education and languages
| Around this street | Wales | |
|---|---|---|
| Degree or other higher qualification, Level 4+ (of adults) | 26% | 32% |
| No qualifications | 31% | 20% |
| Apprenticeship as highest qualification | 6% | 6% |
| Main language English or Welsh (aged 3 and over) | 100% | 97% |
| Cannot speak English well or at all | 0% | under 1% |
Deprivation
The neighbourhood around this street is in decile 6 of 10 on the Welsh Index of Multiple Deprivation 2025, where 1 is the most deprived tenth of Wales's 1,917 neighbourhoods and 10 the least.
What has changed
Nothing new since the change feed started on 30 October 2026. New sales and energy certificates, and hygiene ratings, school inspections and flood figures nearby, will be listed here as the sources update.
Postcodes on this street
Nearby streets
Gwent Court · James Close · Glan-Ddu Road · Cwrt Trelyn · Glanddu Road · Beatty Street · High Street · Beatty Street · Victoria Road · Grey Crescent · Tir Y Berth Industrial Estate · Greys Crescent
All the streets in NP12 and across Caerphilly.
What this page cannot tell you
- Whether a particular house is at risk of flooding, subsiding or anything else: the flood map is a model of areas and there is no property-level data here.
- What a home is worth now: sales are historic prices for the homes that happened to sell.
- How safe the street is: crime points are moved to anonymised locations and many crimes are never reported; road collisions count only those in which someone was hurt and the police were told.
- Whether you would get a place at a school: distances are straight lines, not catchments.
- Who lives on the street now: census figures describe the small areas around it in March 2021, during a lockdown.
- How long a journey takes or how often anything runs: transport distances are straight lines to the nearest stops.
- Whether a GP practice is taking new patients, or a dentist new NHS patients.
- How loud a home is inside, or noise from industry, neighbours or smaller airfields: noise figures are models of road, rail and air traffic outside.
How each figure on this page is matched to the street and worked out: methodology.