Energy refurbishment of an urban commercial building: planning a new envelope

On the hall plan, mark the customer area, workshop, back-of-house areas and rooms heated at different times.

Include information on gate opening times, delivery frequency and the required temperature. This allows the designer to distinguish between the needs of individual parts of the building. Do not assume that a high bill is due solely to wall insulation. Before defining the scope of the renovation, it is worth comparing usage data with an assessment of the building envelope and services.

Changing the thickness of the building envelope affects the installation of doors, windows and gate tracks. Reveal flashings, window sills and the position of thresholds must be checked. With a sandwich panel wall, the way loads from windows and doors are transferred is also important. Dimensions on the old drawing should be compared with a measurement of the existing building.

Junctions between the hall and a masonry section or an adjacent building require particular attention. Mark them separately in the documentation, together with any identified leaks and damage. A finished flashing should not merely conceal an unresolved gap. The connection must account for water, air movement and the intended movement of components.

A roof sandwich panel forms a different system from PIR board laid in an existing roof. In the first case, a complete envelope element is selected together with its support. In the second, all retained layers are assessed along with their interaction with the new insulation and waterproofing. These variants should not be compared solely on the basis of core price.

At parapets and outlets, the available height and the way the layers are terminated must be checked. Choosing thinner insulation with suitable properties may help resolve the detail, but it does not remove the need to ensure water drainage. If equipment is to be installed on the roof, its supports and service access should be part of the design.

In dense development, even a small hall may have difficult access. Determine the vehicle standing position, the unloading point for packs and the duration of occupation of the yard. Long elements require adequate manoeuvring space. Site constraints may affect the division of deliveries and the installation sequence, so they must be known before the panel format is decided.

Plan the separation of the works zone from the customer entrance and from active workstations. The contractor should know which routes must remain accessible and when part of the building can be temporarily closed off. The schedule should also include completion of the flashings: simply fixing the panels does not mean a finished, weathertight envelope.

Before replacing the façade, survey the signage, light fittings, cables and ventilation components. Indicate their future positions and how they will be supported. Do not assume that the new cladding will take all the loads from the old fixings. Agreeing the service routes reduces the number of later openings in the finished surface.

The colour and direction of the panel layout are best assessed on a drawing of the whole façade, together with the gates and the masonry section. The layout should take account of module widths and the required movement joints. A sample helps to check gloss and texture, but does not replace selecting the coating for the local environmental conditions.

Record energy consumption before the renovation and describe the reference conditions: opening hours, use of floor area and temperature. After the works are completed, similar data will allow a fairer assessment of the result. A change in the number of tenants or in the way the hall is used can alter consumption regardless of the quality of the new envelope.

Acceptance should cover documentation, the airtightness of the details and access to components requiring maintenance. In later inspections, pay attention to openings, plinths and roof drainage outlets. Modernisation brings lasting benefit only when the building is used correctly and damage to coatings and joints is not left unrepaired.