FHS-Compliant Heating: A Complete Comparison
The Future Homes Standard mandates low-carbon heating for all new homes from 2025. This is the most significant change in the regulations — and the area where the right design decisions have the greatest impact on both carbon performance and occupant comfort.
Emitter Solutions Comparison
Choosing the right emitter is critical for heat pump efficiency. Each type offers different performance characteristics at the low flow temperatures required by FHS.
| Emitter Type | Flow Temp Range | Response Time | Install Complexity | Noise | Aesthetic Impact | Best For |
|---|---|---|---|---|---|---|
| Underfloor Heating | 35–45°C | Slow (1–6hr) | High (screed embed) | Silent | Hidden | New builds, bedrooms |
| Skirting Board Heating | 35–50°C | Moderate (15–60min) | Low | Silent | Replaces skirting | Whole-house, retrofit |
| Oversized Radiators | 35–55°C | Moderate (15–60min) | Low | Silent | Large wall units | Retrofit, mixed systems |
| Fan Convectors | 35–50°C | Very fast (5–15min) | Moderate | 25–35dB | Wall/ceiling units | High-demand rooms |
Output at Different Flow Temperatures
Heat output drops significantly at lower flow temperatures. Correct emitter sizing is essential — each 1°C reduction in flow temperature improves COP by approximately 2.5%.
| Emitter | Output at 75°C | Output at 55°C | Output at 45°C | Output at 35°C |
|---|---|---|---|---|
| UFH (per m²) | N/A | 80W | 65W | 50W |
| Skirting board heating (per m) | 180W | 120W | 100W | 70W |
| Standard radiator (600×1000) | 1,200W | 720W | 480W | 280W |
| Double panel radiator (600×1400) | 2,100W | 1,260W | 840W | 490W |
| Fan convector (single unit) | 6,000W | 4,200W | 3,200W | 2,100W |
Emitter Types Explained
Detailed analysis of each emitter type — how they work, performance at low flow temperatures, installation considerations, and cost implications.
Underfloor Heating
Underfloor heating distributes warmth evenly across the entire floor surface, operating at the lowest flow temperatures of any emitter type. The large surface area compensates for the low temperature differential, delivering comfortable radiant heat.
Advantages
- Lowest flow temperatures — maximises heat pump COP
- Invisible once installed — no impact on room aesthetics
- Even heat distribution across the room
- Silent operation
Considerations
- Slow response time (1–6 hours) — heat pumps should run continuously to mitigate this
- High installation cost and complexity (screed, floor build-up)
- Difficult to retrofit
- Floor coverings must be compatible (limits carpet options)
Skirting Board Heating
Skirting board heating replaces conventional skirting boards with low-profile heat emitters that run along the perimeter of rooms. The extended linear length provides substantial surface area for heat exchange at low flow temperatures.
Advantages
- Replaces skirting board — no additional wall space required
- Distributed heat around room perimeter reduces cold spots
- Good performance at low flow temperatures
- Simple installation — replaces existing skirting line
Considerations
- Less common — fewer installers experienced with the system
- Limited range of aesthetic finishes compared to radiators
- Moderate response time
Oversized Radiators
Standard radiators can work with heat pumps if significantly oversized (typically 1.5–2× the size required for gas boiler systems). This compensates for the lower flow temperatures by increasing the surface area for heat exchange. At low flow temperatures, response times are moderate — slower than with a gas boiler due to the lower temperature differential.
Advantages
- Familiar technology — well understood by installers
- Moderate response time — comparable to skirting board heating at low flow temperatures
- Easy to install and maintain
- Wide range of sizes and styles available
Considerations
- Must be significantly oversized for low-temp operation
- Large physical presence on walls
- Output drops considerably at low flow temperatures
- May require double-panel plus convectors for sufficient output
Fan Convectors
Fan convectors use an integrated fan to force air across a heat exchanger, dramatically increasing heat output from a compact unit. They deliver the fastest response time of any emitter and work well at low flow temperatures.
Advantages
- Highest output per unit size
- Fastest response time
- Compact installation
- Excellent at low flow temperatures
Considerations
- Fan noise (25–35dB) may be noticeable in quiet rooms
- Requires electrical connection as well as pipework
- Moving parts require maintenance
- Air movement can be perceived as draughty
Heating & Emitter Questions
What heating systems are allowed under FHS?
The FHS does not prescribe specific heating systems but sets carbon reduction targets that effectively require low-carbon heat sources. Compliant options include air source heat pumps (ASHP), ground source heat pumps (GSHP), shared ground loop systems, heat networks (district heating), and potentially hydrogen-ready boilers in specific scenarios. The vast majority of FHS homes will use heat pumps as the primary heat source.
Do I need a heat pump for a new build?
In almost all cases, yes. The 75–80% carbon reduction target under FHS cannot realistically be achieved with combustion heating. Air source heat pumps are the most common choice for individual homes, while ground source heat pumps or heat networks suit larger developments. The specific heat pump type and capacity should be determined by a heating design engineer based on the calculated heat loss of the dwelling.
What size radiators do I need for a heat pump?
Radiators for heat pump systems typically need to be 1.5–2× larger than those specified for gas boiler systems. This is because heat pumps operate most efficiently at flow temperatures of 35–45°C (compared to 65–80°C for gas boilers), and the lower temperature differential means each radiator emits less heat per square metre. A heating engineer should perform room-by-room heat loss calculations and size emitters using the correct delta-T for the design flow temperature.
What are the best emitters for heat pumps?
The best emitter depends on the application. Underfloor heating offers the lowest flow temperatures (35–45°C) and maximises COP but has slow response times (1–6 hours) — heat pumps are typically run continuously to mitigate this. Skirting board heating offers a good balance — operating at 35–50°C with moderate response time while replacing conventional skirting boards, providing distributed heat around the room perimeter. Oversized radiators offer similar moderate response times at low flow temperatures, with the advantage of being familiar technology. Fan convectors deliver the highest output from compact units but produce some noise. Many FHS homes will use a combination of emitter types optimised room by room.
Can I use underfloor heating with a heat pump?
Yes — underfloor heating is one of the best emitter choices for heat pump systems. It operates at the lowest flow temperatures of any emitter type (35–45°C), which maximises the heat pump coefficient of performance (COP). The large surface area of the entire floor compensates for the low temperature. UFH is particularly effective in new-build FHS homes where it can be designed into the floor construction from the outset.
What is skirting board heating?
Skirting board heating is a low-profile heat emitter system that replaces conventional skirting boards around the perimeter of rooms. It uses hydronic (water-based) heat exchangers concealed within skirting-height casings, typically 150mm tall. The extended linear length provides substantial surface area for heat emission at low flow temperatures (35–50°C), making it well-suited to heat pump systems. Installation complexity is low as it follows existing skirting lines.