Cost in use:
There are several areas where cost-in-use benefits arise for concrete-framed buildings, such as:
- Increased durability of the structure, resulting in lower repair and replacement costs.
- Ability to apply a painted finish directly onto the structure, reducing repair and
maintenance costs. - Operational energy savings arising from concrete’s greater thermal mass.
Cost Comparison to competing materials:
A recent study confirmed that ready-mixed concrete offered the most cost effective option in the following structures/projects:
Further advantages:
These represent an additional benefit over and above insulation U-values and can result in lower repair and maintenance costs for mechanical plant. Initial capital cost is not, of course, the sole driver for clients, whose main objective is optimum value from an overall solution.
The wider value aspects of structural solutions in relation to framed buildings are therefore considered further under the following headings:
Acoustics
Fire
Energy efficiency
Sustainability
Acoustics
Acoustic considerations are an important part of the design, with intrusive noise pollution, both within the building and into and out of the building, being detrimental. Factors to consider are the need for mass to reduce transmission of impact noise between floors and the complexity of detailing.
It should be noted that concrete achieves the required acoustic performance with a minimum of extra acoustic finishes.
Fire
Fire resistance is an important issue both in design and in constructability. Fire-proofing to a steel construction generally requires one or more separate trades to follow on after the steel frame has been erected, either using intumescent coatings or fire-resistant boarding.
Concrete is inherently fire resistant and normally requires no added fire protection.
The choice of building material is a factor in fire risk assessments by insurance companies, which recognise the inherent performance of a building material in the event of a fire, and this can affect insurance premiums. Concrete is generally regarded as a robust material that provides an element of safety to property.
Energy efficiency
Structures with a high thermal mass offer potential value to a client. Because of the internal temperatures that have to be maintained in modern buildings, energy efficiency is important.
Thermal mass can be exploited by exposing the soffits, thus utilising Fabric Energy Storage (FES). This reduces initial plant costs by minimising or eliminating the need for air conditioning and substantially reduces the lifetime operating costs of the asset.
Indeed, greater benefits can be achieved by better overall design, taking account of thermal mass and the use of High Strength Concrete (HSC) offering a form of temperature regulation and increased floor space respectively.
Basically, concrete acts as thermal sponge, absorbing heat during the summer and so cooling a building, and storing heat from the sun or heaters to release it at night.
Stabilising effect of thermal mass on internal temperature
Utilisation of FES permits the designer to create naturally ventilated buildings, giving occupants the chance to control their environment, with consequent improvements in employee productivity.
Furthermore, suspended ceilings can be reduced or eliminated, giving valuable initial cost and programme benefits and reduced maintenance costs over the lifetime of the building.
