Converting commercial offices to residential accommodation

1 Introduction
2 Investing in commercial property conversions
3 Guidance for installers
4 Private rented sector
5 Residential flats
6 PAT testing
7 Related articles on Designing Buildings

[edit] Introduction

The growth of online shopping during the COVID-19 pandemic of 2020/2021 has led to empty high streets and town centres. Increasingly, many offices are standing empty. The need for residential accommodation remains high. ‘Starter’ or ‘affordable’ homes are in greatest demand.

For decades, governments of different hues have tried to crack the problem of urban housing. In 2021, the City of London Corporation announced plans to revamp the City by converting commercial office space into residential accommodation.

Solving the problem of inner city housing supply may be a step nearer. Yet, finding a skilled installer to do the work may remain a significant obstacle.

Converting commercial to residential is not new. However, the timing, as we emerge from lockdown in 2021, means the City of London Corporation news resonated with investors. For electrical contractors, and more widely for the construction industry, this presents many opportunities.

[edit] Investing in commercial property conversions

From an investor’s perspective, there is plenty of information about the pros and cons of embarking on such a project. These fall into three main categories.

An increased timeframe. The conversion may require ‘change of use’ planning permission from the local authority. In some cases, this can be done under Permitted Development Rights. Specialist building surveys may be necessary, and a total overhaul of the entire building is possible.
An increased budget. The purchase price of commercial property will incur 20% more VAT than a residential property. However, the property is unlikely to be part of a chain, therefore completion may be quicker.
Profitability. When complete, the conversion is likely to be desirable, therefore of higher value.

[edit] Guidance for installers

Information for consultants and electrical contractors carrying out conversions is limited. Below are some points to consider when converting commercial to residential accommodation.

[edit] Managing expectations

Managing the clients’ expectations is the biggest challenge. When converting offices to residential flats, there is a balance between maximising the number of units (profit) versus delivering desirable places for people to live.

Several Acts of Parliaments, such as the Homes (Fitness for Habitation) Act 2018, may aid discussions. There are also limitations on Listed Buildings. These may affect room size, layout and incorporation of low zero carbon technology.

[edit] Adjusting the load

A commercial building may have several incoming supplies, generators and equipment. The incoming mains for a commercial property may be HV. There may even be HV distribution within the building.

When repurposing a property as residential, the load profile will differ. It is thus probable that less load will be needed. The large capacity of commercial buildings and strict maintenance associated with commercial equipment, such as switchgear, control gear and transformers, will not be necessary.

The layout and supplies for mechanical heating, ventilation and cooling systems are completely different for the two types of properties. These may also affect the electrical distribution and cable routing, thus making it easier to remove all existing services and start again.

[edit] Outdated wiring systems

Wiring systems are likely to be dated, which means they may not be compliant with current regulations (not necessarily a safety risk).

More importantly, the type of wiring system may not be suitable. For example, an office building may have surface-mounted containment systems or run a busbar or Power Trak system as the primary method of electrical (small power) distribution. For a residential building, the inferior aesthetics of such systems may trump the ease of maintenance, further justifying a full overhaul of current services.

[edit] Lighting systems

It is common to find similar issues with lighting distribution. The required lux levels for lighting and the colour rendering index (CRI) of emitted light in a commercial setting will differ to that in a residential setting.

Lighting in offices is selected to encourage productivity. In residential premises the lighting is selected to create a relaxing environment.

BS 7671 (Requirements for Electrical Installations) contain regulations specific only to residential premises. Consider the following when designing the new electrical system:

Regulation 411.3.4 calls for 30 mA additional RCD protection on circuits supplying luminaires.
Regulation 421.1.201 requires consumer units and similar switchgear assemblies to comply with BS EN 61439-3 and either have the enclosure, or be enclosed in a cabinet, made from non-combustible material.
Regulation 462.1.201 says that a main linked switch or linked circuit breaker be used as near as practicable to the origin of every installation. Additionally, in household applications, it shall interrupt both live conductors of a single-phase supply.
Regulation 553.1.201 stipulates for household use, every socket-outlet shall be of the shuttered type and for an AC installation, preferably comply with BS 1363.

[edit] Private rented sector

A residential redevelopment is likely to house tenants. If this is the case, be aware of new English legislation, “The Electrical Safety Standards in the Private Rented Sector (England) Regulations 2020.” This places a duty of care on private landlords to have their properties checked by an electrically skilled person. This legislation came into force on 1 July 2020 for new tenancies.

A satisfactory Electrical Installation Condition Report (EICR) must be available for the period of the tenancy and electrical systems must be re-checked every five years. Houses in Multiple Occupation (HMOs) remain strictly controlled by local authorities and may need licensing from the local council.

[edit] Residential flats

The current distribution for residential flats may be a rising main busbar or cabled. Either way, the system would require modifications to incorporate a metering strategy for multiple flats by utilising Bemco and/or Ryefield units. This also reinforces the idea that a total removal of all services and re-start is the best approach as this would be cheaper and better value for the client.

A selective strip out will involve extra time, as installers attempt to avoid damaging remaining services. The new works will also likely be covered by a warranty as per the contractual specifics.

[edit] PAT testing

A sometimes-overlooked safety element is in-service inspection and testing of electrical equipment (PAT). Any appliance provided by the landlord for use by the tenant is deemed a commercial transaction. These transactions fall under the Health and Safety at Work Act 1974 and by extension the Electricity at Work Regulations 1989.

Specifically, Regulation 4(2) requires maintenance of all electrical systems to prevent danger. Regular inspection and testing of fixed wiring and portable appliances is thus essential.

The Hackitt report into the Grenfell tragedy led to the appointment of a new Building Safety regulator. He will operate under the auspices of the Building Safety Act. This aims to improve safety standards by taking a whole building approach to safety.

ECA supports the holistic approach to building safety. ECA has called for mandatory five-yearly electrical checks and PAT testing. Along with point-of-sale registration for white goods to improve electrical safety in residential premises.

This article originally appeared on the ECA website. It was written by Shahid Khan, Technical Manager, and published on 27 May 2021.

--ECA