Case Study:
Achieving Part L compliance with natural gas

A gas boiler and solar thermal solution, just one of many ways of complying with Part L using natural gas.

Natural Gas and Part L Compliance

Natural gas with a solar thermal solution satisfies Part L by combining a condensing gas boiler with a solar enhanced hot water and heating system. The system, integrated with natural gas, further increases the energy efficiency of your development by delivering free solar energy into the house, providing both space heating and hot water.

Installed using traditional construction and plumbing methods, this means the on-site plumber can install the system without having to employ the services of any third party specialist fitters.

System Features

91.0% Efficient boiler

3 Solalr Thermal Panels of 2.5m2  each

300 litre Stainless steel water cylinder

Smart Rad with fan coil operation

The following input values are used in this example

Building Fabric:

Compliant with U-Value Requirements

Floor: 125mm of PIR insulation   

U-Value of  0.14 W/m2. K

Walls:Full fill bead cavity wall insulation    

U-Value of  0.21 W/m2. K

Roof: 300mm of mineral wool insulation

U-Value of  0.13 W/m2. K

Windows: Double-glazed windows  

U-Value of 1.4 W/m2. K

Heating System:

≥ 90% Efficient Boiler

Main Heating System
The main heating system for this house is a 91% efficient gas fired condensing boiler with standard size radiators.

Heating Controls and Water Storage
Time and temperature zone controls are achieved by a simple time-clock and thermostats within the system. This in conjunction with a 300 litre stainless steel water cylinder (including 160 litres of dedicated solar hot water storage)..

Solar Space Heating
The fan-assisted SmartRad in a common area provides free solar thermal energy reducing the space heating load and at the same time contributes to the renewable thermal heat requirement.

Secondary Space Heating
Natural gas fire in the living room is considered a secondary heating system.


Natural Ventilation throughout the house

The windows are equipped with window vents and all wet rooms include a fan. Current air tightness testing method determined air filtration to be just over 0.25 air changes per hour of floor area.

Renewable Energy Contribution:

10 kWh Thermal Renewable Energy per metre squared per year

The houses in this development have varying orientations. For properties facing south & south-east/west, three flat plate collectors are required. For houses facing east/west, four flat plate collectors are required. Ros Mór easily complies with the thermal renewable energy contribution requirement of 10 kWh per metre squared per year with a thermal equivalent of 18.81 kWh per metre squared per year.

Performance Coefficients:

Carbon Performance Coefficient (CPC) <0.46 & Energy Performance Coefficient (EPC) <0.4

Natural gas as the primary heating system combined with other renewable technologies comfortably meets Part L Building requirements for EPC <0.4 and CPC <0.46. In this development values of 0.357 for CPC and 0.389 for EPC were achieved.

Why BER assessors, developers & consultants should choose this energy solution:

Ease of entry in the DEAP software
When determining the Building Energy Rating (BER) of a new house the entry of anatural gas system with solar thermal panels is a tried and tested method which only requires simple user inputs in the DEAP. Gas Networks Ireland and Nutech Renewables Ltd have worked with many BER assessors, demonstrating the ease of entering this system into the DEAP software. As previously mentioned natural gas as a primary heating system when used in conjunction with renewable technologies easily satisfies all Part L requirements.

Unique Selling Points for the Builder:

Joining the gas network
There are currently over 640,000 domestic gas users on the natural gas network in various locations around Ireland.

Running Costs
This sysytem contributes up to 70% of all hot water requirements, meaning the running costs for the homeowner is considerably less than that of older more traditional space heating hot water installations. Apart from the obvious environmental benefits, the builder leaves a fantastic legacy product for the buyer.

User-Friendliness and Aesthetics
This part L compliant solution incorporates a user-friendly solar control panel. This control panel has two simple settings, Summer & Winter mode, allowing the homeowners to easily select their chosen heating controls for the specific time of year. The aesthetic of the GNI/Nutech combination is far superior to other energy solutions. Just like a traditional gas boiler, the elements of the Nutech solution installed in the house are unobtrusive and compact. There are no aesthetically displeasing units in the garden or in direct view of any prospective home-owner.

Life Cycle and Maintenance
Servicing a gas boiler is a simple process which is performed on an annual basis by one of the many 2,500 Registered Gas Installers (RGIs) around Ireland, traditionally ensuring a prolonged life cycle of 20-25 years. Other heating systems are not as easily maintained and can cost up to 4 times more than servicing a gas boiler. The life expectancy of other heating systems can in some instances be half that of the traditional gas boiler. In addition to this, unexpected replacement of parts can be costly and can cause undue hardship on the future home-owner.

Vendor testimonials

"The system can increase your renewable energy contribution up to four times more than other systems."

Ros Mór Case Study PDF Link

Contact us for the XML files and manufacturers specifications of this worked example.

The contact details for Gas Networks Ireland are:

Networks Services Centre, 
St. Margaret’s Road, Finglas, Dublin 11,

D11 Y895.

General Enquiries:

1850 200 694

24hr Emergency Service:

1850 20 50 50


Renewable Supplier                                                          Developer                                                                    Gas Boiler Supplier

Bill Quigley                                                                           Jana Developments Ltd.,                                              C&F Quadrant Ltd.,
NuTech Renewables Ltd.,                                                    113 North Main Street, Wexford.                                  Unit L40,
PO Box 8008, Glenageary.                                                                                                                                        Cherry Orchard Industrial Estate, Dublin 10.
Tel: 01 663 6372                                                                    Tel: 087 255 1477                                                       Tel: +353-1-630 5757
Email:                                                                                                                          Fax: +353-1-630 5715

Website:                                                                                                                        Email:

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