Underfloor heating: the premium choice for orangeries
Underfloor heating (UFH) is the heating system most consistently specified in London orangeries, and increasingly in high-specification conservatories where building regulations compliance is already required. UFH distributes heat evenly across the entire floor surface, eliminating the cold spots common with perimeter radiators and avoiding the visual intrusion of a radiator on glazed walls where limited solid wall space restricts radiator placement. From a comfort perspective, radiant floor heating is superior to convective radiator heating in a space with high glazing area: warm air from radiators rises and stratifies near the ceiling (where the most heat loss occurs through the glazed roof), while radiant floor heat warms occupants directly, reducing the temperature differential between the floor and the ceiling and improving perceived warmth at lower air temperatures. For orangeries, where the insulated solid roof and thermally broken glazing specification already meets Part L fabric standards, UFH is the natural complement: the structure can retain heat effectively, and the floor mass (150mm concrete slab or 75mm screed over insulated beam-and-block) provides thermal mass that moderates temperature swings. Water-fed UFH from the main house system (combi boiler, system boiler, or heat pump) costs approximately £80–£120/m² for a standard screed installation, or £130–£160/m² for a dry system board installation (suitable for retrofitting over an existing floor without the depth and drying time of a wet screed). Electric UFH mat systems — laid directly under porcelain tiles or engineered wood — cost £40–£70/m² to install but have significantly higher running costs (electricity at 28–34p/kWh vs gas at 5–7p/kWh), making them suitable for rooms used intermittently rather than as the primary heating source. Connecting water UFH to the main house heating system triggers building regulations compliance for the entire structure if the conservatory is not already under building control — this is the most common hidden cost trigger in conservatory projects.
Radiators from the main house system: cheapest but most regulated
Extending the main house central heating system to feed radiators in a conservatory or orangery is the cheapest upfront installation option: a single radiator loop from the existing manifold or a new branch from the nearest pipe run costs approximately £800–£2,500 depending on distance from the boiler and complexity of the pipework route. However, this is the heating option with the most significant regulatory consequences for conservatories. As described in the building regulations context, connecting any conservatory to the main house central heating system removes the Schedule 2 Class 7 building regulations exemption. Once the exemption is lost, the conservatory must comply with Part L energy efficiency requirements — specifically Approved Document L1B (Conservation of Fuel and Power in Existing Dwellings), Table 2, which sets maximum U-values for new extensions: roof 0.15 W/m²K, walls 0.28 W/m²K, floor 0.22 W/m²K, windows and doors 1.4–1.6 W/m²K (whole-unit W/m²K). A standard polycarbonate or glass conservatory roof fails this requirement by a factor of 5–10. This means that any conservatory owner who connects their structure to the main house heating — even by a simple pipe extension — has technically triggered a building regulations obligation to upgrade the entire thermal envelope of the structure to Part L standards. In practice, building control enforcement of this triggering is rare, but it creates a compliance gap that will emerge as a defect on conveyancing during property sale. Buyers' solicitors will ask for building regulations completion certificates for any visible radiators in a conservatory — if the certificate does not exist, it becomes a negotiation point or indemnity insurance requirement.
Electric panel heating: quick installation, high running costs
Standalone electric panel heaters, infrared heating panels, or electric convector heaters can be installed in a building regulations-exempt conservatory without triggering Part L compliance — provided they are on a separate electrical circuit (not thermally connected to the main house heating system) and do not draw from the house central heating circuit. This makes electric heating the simplest compliance-neutral option for conservatories where the owner wants some heating capability without losing the Schedule 2 exemption. Electric infrared panels are increasingly popular in conservatories because they provide radiant warmth directly to occupants rather than heating the air (which is more quickly lost through glazing), they can be ceiling or wall mounted without affecting the appearance of glazed walls, and they are available with thermostatic control and timer programming. Supply cost for a panel suitable for a 20m² conservatory: £400–£900. Installation by a Part P-registered electrician: £300–£600. Total installed cost: £700–£1,500 — significantly less than a UFH or radiator system. The disadvantage of electric heating — whichever form — is running cost. At 2025 electricity prices of 28–34p/kWh, an electric panel running at 2kW for 4 hours per day costs approximately £840–£1,020 per year. The equivalent heat output from a gas boiler at 5–7p/kWh costs £140–£200 per year. Electric heating at £800+ per year running cost is appropriate only for rooms used intermittently or seasonally — a conservatory used primarily in spring and autumn rather than as a full-time habitable room. For year-round use, heat pump or gas-based heating is significantly more economical.
ASHP split units: high efficiency with planning implications
Air-source heat pump (ASHP) split units — wall-mounted indoor unit, external compressor unit — are emerging as a technically compelling heating and cooling solution for conservatories and orangeries, particularly as building regulations Part L requirements push all new work towards lower-carbon heating systems and as the Future Homes Standard (expected from 2025–2026) tightens requirements on fossil fuel heating in extensions. An ASHP split unit delivers heating efficiencies of 250–350% (COP 2.5–3.5, meaning 2.5–3.5 kWh of heat per kWh of electricity consumed), making it three to four times more energy efficient than direct electric panel heating and broadly equivalent to gas at 2025 energy prices. For a 20m² conservatory or orangery, a 2.0–3.5kW heating capacity wall-mount split unit from Daikin, Mitsubishi, or LG costs approximately £1,500–£2,500 supply, with installation (refrigerant pipe run, electrical connection, condensate drainage, external unit siting) at £800–£1,500 — total installed cost of £2,300–£4,000. The unit provides both heating and cooling, which is a meaningful benefit in glazed structures that overheat in summer. The planning implication is the external compressor unit. Under the Town and Country Planning (General Permitted Development) (England) Order 2015, air-source heat pump installations have their own PD right (Class G) but with conditions: the unit cannot be installed on a wall or roof that faces a highway, must not be within 1m of the property boundary, must not exceed 0.6m³ in volume, and must be at least 1m from any other heat pump on the same property. In conservation areas, Class G PD for ASHPs is removed, and a planning application is required for the external unit. For orangeries and conservatories in conservation areas, planning for the ASHP is therefore an additional step that must be managed alongside the main extension application.
