What does an MEP engineer do on a residential project?
Part of our consultant series
This post is part of our ongoing series explaining the different consultants typically involved in a residential project. Each plays a distinct role in delivering a well-coordinated, compliant and buildable design. Understanding what each consultant does helps clients see how the wider team works together and when their input becomes essential.
Our overview blog post introduced all of the varying consultants you may need to involve on a high end residential project with links to the various blog posts detailing each of the roles.
What is an MEP consultant?
An MEP consultant is a specialist engineer responsible for the design and coordination of the mechanical, electrical and public health systems in a building. The acronym “MEP” stands for Mechanical, Electrical and Plumbing (or Public Health). Together, these systems determine how a house feels and functions on a day-to-day basis, from heating, cooling and ventilation to lighting, power, water, drainage and sometimes renewables.
On a residential project, especially one involving significant refurbishment, extension or new build, the MEP design underpins comfort, sustainability and efficiency. The consultant’s role is to make sure that services are integrated seamlessly into the architecture without compromising the design intent.
When an MEP consultant is required
A small refurbishment or internal redecoration will rarely need an MEP consultant, as a competent contractor can work to standard specifications. However, once a project involves new heating or cooling systems, complex lighting, underfloor heating, smart home automation, or significant changes to drainage or ventilation, an MEP consultant becomes essential.
Typical situations where an MEP consultant is appointed may include:
Whole-house refurbishments where existing systems are being replaced
New build homes, where all services must be designed from first principles
Listed or period buildings, where sensitive coordination is needed to hide new services
Basement or mansard extensions, which often require new plant, ventilation and drainage strategies
High-performance homes, including low-energy or net-zero schemes, where mechanical systems must meet strict efficiency standards
A sketch showing the hidden services such as hot water, ventilation and electrics that allow a house to function properly.
What an MEP consultant actually does
An MEP consultant begins by understanding the client’s priorities - comfort levels, sustainability goals, smart systems, and visual preferences. They then produce coordinated designs covering:
Mechanical systems: heating, cooling, ventilation, and any renewable technologies such as heat pumps or solar thermal systems.
Electrical systems: power distribution, lighting layouts, emergency lighting, security, AV, data and home automation.
Public health systems: cold and hot water, waste water, rainwater harvesting, and drainage connections.
They produce drawings and technical schedules showing plant locations, routes for ductwork and pipework, and connection points to equipment. The consultant ensures that the systems are both technically compliant and practically achievable within the spatial constraints of the building.
How the MEP consultant interfaces with the architect
Close coordination between the architect and MEP consultant is vital. Services routes, plant positions and ventilation terminals all need to be planned early to avoid clashes or unsightly outcomes. The architect ensures that grilles, switches, light fittings and controls are integrated neatly into the design, while the MEP consultant provides the technical data and performance specifications to make them work efficiently.
At Nancy Gouldstone Architects, the MEP design is typically developed alongside the architectural and structural design from RIBA Stage 3 onwards. This allows early decisions about ceiling depths, risers, plant rooms and external units to be resolved before construction drawings are finalised.
Coordination with other consultants
The MEP consultant also works with the structural engineer to coordinate service penetrations through walls, floors and beams. They liaise with the fire engineer to ensure that fire dampers, smoke ventilation and detection systems are compliant, and with the sustainability or energy consultant where calculations are required for Building Regulations compliance (Part L).
If the project includes smart home systems or a specialist lighting designer, the MEP consultant provides the technical infrastructure to support their designs.
Legislation and standards
MEP design must comply with a range of UK legislation and Building Regulations. The most relevant parts for residential projects are:
Building Regulations Approved Document Part L – sets requirements for energy efficiency of heating, lighting and hot water systems, including limits on heat loss and system controls.
Part F – covers ventilation, including extract rates, air quality and prevention of condensation.
Part G – governs sanitation, hot water safety, and water efficiency.
Part P – ensures that electrical installations are designed and carried out safely by competent persons.
Part B – covers fire safety and influences MEP design through requirements for fire alarms, smoke ventilation and dampers.
In addition to the Building Regulations, MEP consultants also follow relevant British Standards (for example BS 7671 for electrical installations and BS EN 12831 for heating load calculations) and, on larger or more complex projects, CIBSE Guides (Chartered Institution of Building Services Engineers).
For listed or period buildings, further guidance may come from the Local Planning Authority and Historic England, especially where introducing new plant or external grilles might affect the building’s character.
During construction
Once on site, the MEP consultant may review contractor drawings, check equipment submittals, and carry out periodic inspections. They can also assist the contract administrator or project manager in reviewing mechanical and electrical variations, as these often represent a significant portion of the build cost.
At the end of the project, they may witness system testing and commissioning, ensuring everything performs as intended. Larger projects may also involve producing an operation and maintenance manual, detailing how each system should be used and serviced.
Appointing the right consultant
MEP engineers vary in scope and approach. Some specialise in large commercial projects, while others focus on residential and high-end domestic work. The right consultant for a house project should understand the subtleties of working in period buildings, limited ceiling spaces, and the visual priorities of architectural design.
A good MEP consultant will design systems that are discreet, reliable and easy to maintain, contributing to a comfortable and efficient home without drawing attention to the engineering behind it.