Air conditioning in Knebworth
We install, service and repair air conditioning in Knebworth, Old Knebworth and the villages nearby. Knebworth has three conservation areas and an Article 4 direction at Stockens Green, so here's exactly what they cover and where an outdoor unit can go.
- Knebworth station opened
- 1884
- conservation areas in the parish
- 3
- single room, from
- £1,850
- annual service, from
- £119
North Hertfordshire in official figures
- households (2021 Census)
- 56,732
- live in a flat
- 20 in 100
- live in a house
- 80 in 100
- listed building entries
- 1,747
Of 56,732 households in the 2021 Census, 80 in 100 lived in a house (24 detached, 31 semi-detached, 25 terraced) and 20 in 100 in a flat. Most installs here are on houses, where a back or side wall is usually the simplest place for the outdoor unit.
In a conservation area an outdoor unit can't go on a wall or roof facing a road without planning permission, and an Article 4 direction can remove permitted development rights altogether. Check your postcode to see whether either applies to your street.
Figures for the whole North Hertfordshire council area. Sources: ONS Census 2021, table TS044 (accommodation type); Historic England's National Heritage List entries within the council boundary, through planning.data.gov.uk (one entry can cover several buildings). Checked October 2026.
A village that moved twice
The North Herts Local Plan explains that Knebworth has moved twice. The first village stood in what is now Knebworth Park, around the church of St Mary and St Thomas, which is listed grade I and now stands alone in the park. An owner of Knebworth House moved the village out to enlarge the park, to what is now Old Knebworth. Today's Knebworth then grew up around the railway station, a little to the east.
The council's conservation area appraisals date that growth to the opening of Knebworth station in 1884. In 1910 a plan for a Knebworth Garden Village on the Earl of Lytton's land was drawn up by Thomas Adams with Edwin Lutyens, who had married Lady Emily Lytton. It was never realised, but Stockens Green was built as a small garden suburb in its spirit, and Lutyens designed several houses nearby, including two on Deards End Lane. The A1(M) now divides Knebworth from Old Knebworth.
Knebworth homes and what they mean for an install
The ONS counts about 4,195 people in the Knebworth built-up area (Census 2021). Homes are a mix: 29 per cent semi-detached, 28 per cent detached, 19 per cent terraced and 24 per cent flats.
| Type of home | Typical areas | What it means for the install |
|---|---|---|
| Arts and Crafts cottages in pairs and short terraces | Stockens Green and Gun Lane | Conservation area, and many houses have an Article 4 direction on the road-facing side. Rear position only. |
| Lutyens houses and 1920s and 1930s detached houses | Deards End Lane and Park Lane | Conservation area, some listed. A garden or rear position, agreed before booking. |
| Houses from the 1880s onwards, and later semis | The main village around the station and the High Street | Usually permitted development. A rear wall or ground pad, and a multi-split for several bedrooms. |
| Flats | Across the main village | Freeholder consent first. Permitted development allows one heat pump per block, with an outdoor unit up to 0.6 m³. |
| Cottages and farmhouses | Old Knebworth and Nup End, west of the A1(M) | Conservation area and many listed buildings. Expect consent and a carefully chosen position. |
Planning: North Hertfordshire Council
Knebworth is in North Hertfordshire, not Stevenage or Welwyn Hatfield, so planning goes to North Herts Council. A heating-capable outdoor unit on a house is often permitted development if it is not used only for cooling, is no bigger than 1.5 m³ and passes the MCS 020(a) noise check of 37 dB(A) at neighbours' windows. A semi or terrace can have one heat pump, a detached house two. Our planning guide has the rest.
In a conservation area, a unit can't go on a wall or roof that fronts a road under permitted development, and listed buildings need listed building consent. Knebworth also has a neighbourhood plan, made in May 2022 after a referendum on 5 May 2022, which the council uses in planning decisions in the parish.
Knebworth's three conservation areas
| Conservation area | What it covers | Designated |
|---|---|---|
| Old Knebworth | The village west of the A1(M), Knebworth House (grade II*), the grade I church and Nup End. 27 listed buildings | 6 October 1969, amended 1990 |
| Deards End Lane | Deards End Farm's listed barns, three grade II Lutyens buildings (the Golf Club House, Wych Elms and Beacon House) and 1920s and 1930s houses | 2 April 1984 |
| Stockens Green | A co-partnership garden suburb begun in 1912, with houses in pairs and short terraces around the green and on Gun Lane | 2 April 1984, amended 1990 |
Dates from the council's appraisals: Deards End Lane and Stockens Green (approved April 2008) and Old Knebworth (adopted September 2011). Check the council's maps for exact boundaries.
The Stockens Green Article 4 direction
North Herts Council made an Article 4(1) direction for part of the Stockens Green conservation area on 9 October 2012 and confirmed it on 21 March 2013. It covers 9 and 11, 10 to 64 (even numbers), 17 to 43 (odd numbers) and 47 to 57 (odd numbers) Stockens Green, and Beechcroft on Gipsy Lane.
It takes away permitted development rights for: extensions and alterations that front a highway; changes to a roof slope that fronts a highway; porches on a door that fronts a highway; hard surfaces that front a highway; chimneys, flues and soil and vent pipes; gates, fences and walls that front a highway; and painting the outside of a house where it fronts a highway.
The direction doesn't list the heat pump right, which is a separate class. But an outdoor unit facing the road isn't permitted development in a conservation area anyway, and pipework or alterations on the road-facing side could fall under the direction. So at these addresses we only plan rear positions, with pipes through the back wall, and ask the council if anything would show from the road.
New homes in Knebworth
The North Herts Local Plan 2011–2031, adopted on 8 November 2022, allocates three sites: KB1 Land at Deards End for about 200 homes, KB2 Land off Gipsy Lane for about 184 homes with land for a new primary school, and KB4 Land east of Knebworth for about 200 homes. The plan asks for noise mitigation on KB1 and KB2, and for sensitive design next to the Deards End Lane and Stockens Green conservation areas.
If you buy one of the new homes, check its planning conditions before adding an outdoor unit. Some new estates also have covenants about outside equipment.
Shops, businesses and parking
We fit and service air conditioning in shops, cafes, clinics, salons and offices on the High Street and Station Road. Wall units suit shops and small rooms; ceiling cassettes suit offices with suspended ceilings. Commercial installs are done in business hours.
North Herts Council manages on-street parking. The parish council lists restricted bays on the High Street, Station Road and Kerr Close, and says the Milestone Road and Pondcroft Road parking is controlled, with two hours free and no return. Tell us when you book and we'll plan where the van can unload the outdoor unit.
What air conditioning costs in Knebworth
Our starting prices are the same here as across Hertfordshire and London. Home prices include VAT. Business prices are plus VAT. Planning fees, if needed, are separate.
- from£1,850inc. VAT
A bedroom or study
2.5 kW wall unit, 5 m pipe, fitted in a day
- from£2,050inc. VAT
A living room
3.5 kW wall unit
- from£3,650inc. VAT
Two rooms, one outdoor unit
Multi-split
- from£5,100inc. VAT
Three rooms
Multi-split
- from£2,350inc. VAT
Floor-standing unit
2.5 kW console
- from£250inc. VAT
Premium range upgrade
Quieter, more efficient unit
- from£1,795+ VAT
Commercial wall unit
Fitted in business hours
- from£119inc. VAT
An annual service
Keeps the manufacturer warranty valid
Areas and postcodes we cover
We cover the whole parish and the villages around it, including:
- SG3: Knebworth, Stockens Green, Deards End Lane and the roads around the station
- SG3: Old Knebworth and Nup End
- Nearby: Woolmer Green, Datchworth, Codicote, Welwyn and Stevenage
Knebworth questions
Do I need planning permission for air conditioning in Knebworth?
Often not, if the unit also heats and meets the size, position and noise limits. You need permission for a cooling-only unit, a unit on a wall facing the road in one of the three conservation areas, or any work to a listed building, which also needs listed building consent. Applications go to North Herts Council.
I live on Stockens Green. Does the Article 4 direction stop air conditioning?
No, it doesn't name the heat pump right. It removes rights for road-facing alterations, porches, roof slopes, walls and fences, hard surfaces, painting, and chimneys, flues and vent pipes. A unit at the back, with the pipe through the rear wall, is the usual answer. If anything would show from the road, ask the council first.
My house on Deards End Lane is listed. What's involved?
Listed building consent, and planning permission if the unit would face the road. We survey first, suggest a garden or rear position and give you the unit's size, sound data and a marked-up plan for the application. We book the install once consent comes through.
Is Knebworth planning dealt with by Stevenage?
No. Knebworth is in North Hertfordshire, so applications go to North Herts Council. Under the July 2026 decision, subject to Parliament, Stevenage and most of North Herts and Welwyn Hatfield are due to form a new central Hertfordshire council from 1 April 2028.
What does it cost to cool two bedrooms in a Knebworth semi?
Two rooms on one outdoor unit start from £3,650 including VAT, using a multi-split. A semi can have one heat pump under permitted development, so one outdoor unit for both rooms keeps it simple. We give you a fixed written price after the survey.
Do you service and repair existing systems?
Yes. An annual service starts at £119 including VAT, plus £59 for each extra indoor unit on the same visit. We repair most brands, whoever fitted them, and confirm the cost of the repair visit when you book.