Building Services Engineer Interview Questions UK: 8 Real Questions and What Interviewers Want

Applying for a Building Services Engineer job in the UK? Here is what you are likely to be asked. These questions come from our Building Services Engineer question bank of 16 questions, written for UK employers at mid-level level.

Eight Building Services Engineer interview questions, and what the interviewer is thinking

1. What does a building services engineer do day to day, and what made you choose this specialism over structural or civil engineering?

Why they ask: They want to see that you understand the role's scope and have a genuine reason for choosing it.

2. Walk me through the RIBA Plan of Work stages and what a building services engineer produces at each one.

Why they ask: They want to confirm you understand how the design process is structured and what is expected at each stage.

3. How would you approach designing the ventilation for a new open-plan office floor?

Why they ask: They want to see a logical design method and knowledge of the key criteria and guidance.

4. How do you size the electrical supply and cables for a building, and what do you check on voltage drop?

Why they ask: They want to see competence in electrical design fundamentals and awareness of BS 7671.

5. How would you size heating or chilled water pipework and select a pump?

Why they ask: They want to see whether you can apply hydraulic principles accurately in practical design.

6. What would you consider when designing the lighting for a workspace, and which standards apply?

Why they ask: They want to check knowledge of lighting criteria, energy efficiency and emergency lighting.

7. The client's cost consultant proposes removing standby plant from your design as a value engineering saving. How do you respond?

Why they ask: They want to see whether you can weigh resilience, risk and cost in a conversation with a commercial stakeholder.

8. Tell me about a time you had to deliver a design package on time when information from other consultants was incomplete.

Why they ask: They want to see how you manage dependencies and risk in a multidisciplinary design process.

A sample answer to question 1

What does a building services engineer do day to day, and what made you choose this specialism over structural or civil engineering?

A building services engineer designs the systems that make a building work for the people in it: heating, ventilation, cooling, electrical power, lighting, public health and fire protection. Day to day I run calculations and models, produce drawings and specifications, coordinate with architects and structural engineers, answer contractor queries and attend design team meetings, with occasional site visits to check progress. I chose it because it sits between physics, energy and people. The decisions I make affect comfort, health and carbon emissions for the entire life of the building, and buildings account for a large share of the UK's energy use, so the work is important to the net zero agenda. I also enjoy the variety: a school, a hospital and an office raise entirely different problems. Compared with structural or civil work, I like that the design is about performance over time, and that the engineering is more heavily influenced by how people actually use a building.

Common mistake to avoid: Listing only HVAC; no real reason for the choice

Want the rest?

Full model answers, key points and common mistakes for all 16 questions are on the Building Services Engineer interview questions page. The first five are free, no sign-up needed.