Air conditioning in Welwyn

Welwyn, not Welwyn Garden City

Welwyn is the old village north of Welwyn Garden City, on the far side of the Mimram valley, and much smaller: the council's own conservation area appraisal says it is now overshadowed by its larger neighbour. They share a council, Welwyn Hatfield, but they are different places with different rules: Welwyn Garden City's Estate Management Scheme is a garden city scheme, while Welwyn village has its own conservation area and, since June 2026, its own neighbourhood plan.

If you live in the garden city, our Welwyn Garden City page explains the Estate Management Scheme. This page covers Welwyn village and the rest of Welwyn parish: Digswell, Oaklands and Mardley Heath.

A village on the Great North Road

The council's Local Plan describes Welwyn as an ancient settlement built round a ford at a bend of the River Mimram. In Roman times it stood on the road between St Albans and Colchester, and the bathhouse of a Roman villa can still be seen in a vault under the A1(M). The 2024 conservation area appraisal records that the Great North Road came through the village from the 16th century, with a turnpike trust from 1725, although Welwyn never fully grew into a coaching town.

The village stayed compact in the valley until the 20th century. The appraisal says it began to grow after the by-pass was built in 1926, with later housing along Prospect Place and north of Lockleys Drive and Church Street. Today the A1(M) runs along its eastern edge, with direct access at junction 6.

Welwyn homes and what they mean for an install

The ONS counts about 3,905 people in the Welwyn built-up area (Census 2021). A third of homes are semi-detached houses, a quarter detached and a quarter terraced.

The Welwyn conservation area

The historic core was designated a conservation area in 1969 but had no character appraisal until Welwyn Hatfield Borough Council adopted one after Full Council on 13 March 2024. The same decision amended the boundary, taking out modern housing such as the Parkside estate, Welwyn Hall Gardens and a few newer houses that lack historic interest. If you live near the edge, check the new map.

The appraisal counts 52 listed buildings in the conservation area. One, Guessens on Codicote Road, is grade II* and the rest are grade II. It describes soft Hertfordshire red brick, often painted white or cream, with timber-framed rendered buildings, yellow stock brick terraces, and roofs of slate and clay plain tiles. It warns that piecemeal changes to windows, doors and roofs harm the area more than anything else, so we keep units and pipework off the street side and away from historic details.

Planning: Welwyn Hatfield Borough Council

Planning in Welwyn is handled by Welwyn Hatfield Borough 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-detached or terraced house can have one heat pump, a detached house two. Our planning guide has the rest.

In the conservation area, a unit can't go on a wall or roof that fronts a road under permitted development. Listed buildings need listed building consent for a unit or a pipe hole, wherever it goes. When we checked in October 2026, the national planning data showed no Article 4 direction covering the village centre.

In July 2026 the government announced that Hertfordshire's councils will be replaced by four unitary councils from 1 April 2028, subject to Parliament. Welwyn would join a new central Hertfordshire council. Until then, Welwyn Hatfield decides applications.

Digswell

Digswell sits across the Mimram from Welwyn, around Welwyn North station. The neighbourhood plan explains that today's Digswell grew from the mid-19th to the mid-20th century around the station, in an area first called High Welwyn, beside the much older hamlet of Digswell Water. The Local Plan describes low density housing with larger houses and gardens, and the Digswell Viaduct, which carries the East Coast Main Line across the valley, is listed grade II*.

Digswell isn't a conservation area, so most houses can have a unit under permitted development. The council still uses its 2003 Digswell Character Appraisal in decisions, and the neighbourhood plan asks for effective screening from the road and neighbours. A side or rear position, screened by planting, fits both.

Oaklands and Mardley Heath

Oaklands and Mardley Heath runs along the B197 between Welwyn and Woolmer Green. The Local Plan describes large houses in big gardens, many of them reached by private, often unmade roads on sloping ground. The ONS figures show how detached it is: about 79 per cent of homes in the Oaklands built-up area are detached houses or bungalows.

A detached house can have two heat pumps under permitted development, so a larger home can have two outdoor units, or one multi-split serving three or four rooms. On private unmade roads and slopes, we check van access and where the unit can stand level when we survey.

New homes in the parish

The Welwyn Hatfield Local Plan 2016–2036, adopted in October 2023, allocates three sites in Welwyn village: HS18 The Vineyards for about 30 homes, HS19 Sandyhurst for about 30 and HS20 School Lane for about 9. It allocates sites in Oaklands too, and none in Digswell. If you buy a new home, check its planning conditions before adding an outdoor unit.

Shops, offices and parking

We fit and service air conditioning in shops, cafes, pubs, salons, clinics and offices on the High Street and Church Street. Many of these are in listed buildings, so we start with the siting and the consents before quoting the work.

Welwyn Parish Council keeps six car parks in the village free all day, but several have height barriers. Mimram Road is narrow and the appraisal notes that parking there makes access difficult. Tell us when you book and we'll plan where the van can unload the outdoor unit.

What air conditioning costs in Welwyn

Our starting prices are the same here as across Hertfordshire and London. Home prices include VAT. Business prices are plus VAT. Consent fees, if any, are separate.

• A bedroom or study

  2.5 kW wall unit, 5 m pipe, fitted in a day

  from£1,850inc. VAT

• A living room

  3.5 kW wall unit

  from£2,050inc. VAT

• Two rooms, one outdoor unit

  Multi-split

  from£3,650inc. VAT

• Three rooms

  Multi-split

  from£5,100inc. VAT

• Four rooms

  Multi-split

  from£6,500inc. VAT

• Premium range upgrade

  Quieter, more efficient unit

  from£250inc. VAT

• Commercial wall unit

  Fitted in business hours

  from£1,795+ VAT

• An annual service

  Keeps the manufacturer warranty valid

  from£119inc. VAT

Areas and postcodes we cover

We cover the whole parish and the villages around it, including:

• AL6: Welwyn village, Digswell and Digswell Water
• AL6: Oaklands, Mardley Heath and Burnham Green
• Nearby: Woolmer Green, Codicote, Knebworth and Welwyn Garden City

Welwyn questions