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Steel Designers' Manual - 6th Edition (2003)
282 Sustainability and steel construction
Table 8.1 Comparison of thermal performance of light steel frame residential buildings with UK
Building Regulations
U-values (W/m 2 K) Walls Floor Roof Windows
1995 Building Regulations 0.45 0.45 0.25 3.3
2002 Building Regulations 0.35 0.25 0.20 2.2
Good practice 1
0.35 0.32 0.20 2.8
Ultra-low energy homes 2
0.20 0.20 0.15 2.0
Low energy steel frame house 3
0.20 0.35 0.20 1.8
Notes:
1. Good Practice Guide 79 – Energy efficiency in housing, Department of Environment, 1993.
2. General Information Report 38 – Review of ultra-low energy homes, Best Practice Programme of the
Department of Environment, 1996.
3. U-values of the Oxford Brookes University Demonstration Building.
• Minimization of heat loss through the building envelope
• Provision of an airtight building envelope with controlled ventilation
• Provision of efficient and controlled heating
• Use of appropriate passive heating, cooling and ventilation methods.
These measures can often be achieved at little or no extra overall cost, particularly
where savings can be made in the capital cost of heating systems as a result of additional
insulation and airtight construction. To accompany the regulations, a document
is being developed showing robust details of plans which will, if properly
constructed, give compliance with the UK Building Regulations. To achieve compliance
with the new regulations 5 will be easier with framed construction than
with traditional methods.
Light steel frame housing has several generic advantages but as with all forms
of construction attention should be paid to the detailing in order to maximize the
benefits.
Placing the insulation on the outside of the frame is known as warm frame construction;
this minimizes heat loss since there is minimal thermal bridging. Risk of
condensation is eliminated since all the members are contained within the warm
internal environment. High levels of insulation are possible however without
significantly increasing wall thickness by the addition of insulation between the
frame members. Heat loss resulting from air infiltration can also be conveniently
minimized by the inclusion of an air tight membrane in the walls.
8.6.2 Commercial buildings and operational energy
Commercial buildings use energy primarily for space and water heating, lighting,
cooling, ventilation and small power. In order to reduce operational energy, buildings
should be designed to provide maximum occupant comfort throughout the year
with minimum energy requirements. The charts in Fig. 8.2 show typical energy
requirements and carbon dioxide emissions for two types of commercial building.