Anyone developing a site that needs a new gas supply will, at some point, face a choice between two ownership models for the new network: a Gas Distribution Network (GDN) or an Independent Gas Transporter (IGT). The choice affects upfront cost, adoption process, and how the gas bill is structured for the end user.
This guide explains what each one is, how they differ, and which to use for different project types.
Definitions
A Gas Distribution Network (GDN) is one of the four regional monopoly networks licensed by Ofgem to operate the UK gas distribution system. The GDNs are Cadent, Northern Gas Networks, SGN, and Wales and West Utilities. They own and maintain the existing gas mains and pressure reduction infrastructure.
An Independent Gas Transporter (IGT) is a licensed company that builds, owns, and operates new gas networks connected to the GDN system. IGTs compete with the GDNs for the contestable portion of new connection work and retain ownership of the assets they install.
Both are regulated by Ofgem. Both must comply with the same safety standards. The difference is ownership and commercial model.
The GDN Model
Under the GDN model, new gas mains and service pipes installed on a development are adopted by the GDN once they meet the adoption criteria. The GDN then owns and maintains them as part of its distribution network. Residents or occupiers buy their gas from a retail supplier and pay the standing charge and unit rate set by the market, with the GDN receiving the transportation charge through the supplier.
The upfront cost to the developer is typically higher under the GDN model because the GDN’s asset value is recovered through the connection charge.
The IGT Model
Under the IGT model, the new gas mains and services are owned by the IGT. The IGT recovers its investment through an annual transportation charge that is bundled into the end user’s gas bill. Because the IGT amortises the asset over time rather than recovering it upfront, the developer pays a lower connection charge.
The end user still buys gas from any retail supplier they choose. The IGT’s charge is automatically passed through the supplier’s billing system. End users rarely notice they are on an IGT network because the bill looks the same.
Cost Comparison
For a typical housing development, the connection cost under the IGT model can be 30 to 60 per cent lower than the GDN equivalent. On a 100-plot scheme, this can translate to savings of £40,000 to £90,000.
The trade-off is that residents on an IGT network pay a marginally higher transportation charge on their gas bill, typically one to three pounds per month. The difference is often invisible in the retail price comparison.
For a commercial standalone site, the savings on an IGT connection are smaller in percentage terms because the cost structure is different, but the model can still be attractive, particularly for sites with heavy loads or complex civils.
Adoption and Ownership
Under the GDN model, the new assets are adopted by the GDN after installation, commissioning, and a snagging period. From that point on, the GDN is responsible for maintenance, repairs, and any future modifications.
Under the IGT model, the IGT retains ownership permanently. The IGT is responsible for all maintenance and repairs, and the end user’s statutory rights to safe gas supply are unchanged.
For the developer, the IGT model usually offers a simpler adoption process because the IGT carries out both the design and installation and does not need to hand assets over to a third party.
Timelines
IGT projects are often quicker to deliver than GDN-led projects because the IGT controls design, civils, and commissioning under one roof. GDN-led projects involve more hand-offs between teams.
Typical housing development timelines:
IGT route: eight to twelve weeks from contract to first gas on. GDN route: twelve to twenty weeks from contract to first gas on.
Both can be shorter or longer depending on site conditions, but the IGT model generally has the edge on programme.
When to Use a GDN
There are cases where going directly through the GDN is the right call.
If the site is a single domestic connection off an existing main, the GDN model is often the default.
If the local authority or planning condition requires GDN adoption, there is no choice.
If the end user has a strong preference for GDN ownership (some large corporate clients do), that preference drives the decision.
If the connection involves complex interaction with the existing GDN network (for example, a medium-pressure connection that affects network capacity), the GDN route can be simpler.
When to Use an IGT
The IGT route is usually the better choice for:
Housing developments of 20 plots or more, particularly in the housing and high-rise residential sector.
Mixed-use schemes where gas is part of a wider utility package.
Commercial sites where cost certainty and programme control matter more than asset ownership.
Projects where the developer wants a single point of contact for the gas infrastructure.
How to Decide
Get quotes from both an IGT and the relevant GDN (or, more practically, from a UIP who can offer both routes). Compare upfront cost, lead time, and delivery risk.
If there is no strong external driver for one model over the other, the decision usually comes down to money and programme. On most housing developments, that points to the IGT route.
The Bottom Line
IGTs are not a workaround or a loophole. They are a regulated part of the UK gas market, and they exist precisely to introduce competition into new gas connections. For any developer doing a meaningful volume of gas connection work, understanding the IGT option and when to use it is one of the easier wins on overall project cost. The similar logic for electricity, where IDNOs compete with DNOs, is also worth knowing.