Materials Spec

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Introduction

The full material specifications for this project are available as a pdf. As with all construction projects not all the ideas that were proposed in the original schedule have been realized.  Other reports comment on what items were not actioned and the reasons behind it.

The Lower London Road Sustainable Housing Project will be the first major sustainable housing project in Scotland to define a better way of building the kind of houses that people want to live in. The programme is based around the building of a number of blocks of traditional timber-frame flats, much the same as those being built all over the country on a daily basis. The difference is that Lower London Road will be built to have the lowest practicable environmental impact throughout the lifetime of the development.

This document sets out the specifications required for each of the main construction materials to be used in the project. The method used to decide on the final specification is outlined below.

In essence, the method includes three main considerations:

the environmental performance of each material (in terms of production, operation and recycling / disposal),
the cost of the material compared to the standard material that would normally be used,
the operational performance of the material (taking into account the extended design life of the building).

These considerations are not taken in isolation but compared against each other for each option so that, for example, the increased cost of a material would be acceptable if it was matched by improved environmental and operational performance. Similarly, a significant increase in the cost of a particular material compared to the standard might not be acceptable if it was felt that the same amount of money spent elsewhere would have a greater environmental or operational benefit.

Environmental and operational benefits were also compared against each other for each option. A material might be particularly durable, for example but be unacceptable in environmental terms, or conversely it could be felt that the adverse environmental impacts of a particular material were outweighed by its operational benefits.

Although every effort has been made to take into account the latest information from life cycle assessments and report findings, these decisions will eventually be based on a subjective judgement. One of the main aims of the Lower London Road Sustainable Housing Project is to encourage future sustainable development by clearly stating what decisions have been made and on what basis. This will allow future developers to judge the best sustainable option for them, based on their own subjective impressions of comparative environmental impacts and on the up-to-date information of the day. To this end, this document contains information on those materials which were not selected, as well as those which were and seeks to explain the decision-making process behind the specification.

An adaptation of the Dutch "Environmental Preference Method" has been used to set this specification. This method compares materials and products currently on the market and ranks them according to their environmental impact. It considers environmental impacts throughout the whole lifecycle of a material, including the extraction, production, building, occupational and recycling phases. Thus, for example, a higher environmental impact during construction could be justified by improved performance throughout the life of the building.

This method has been adapted to include local availability and economic viability. It has also been revised to take into account the extended design life of this development and the requirements of the relevant building regulations.

The main sustainability issues considered in the assessment are:

shortage of raw materials
ecological damage caused by the extraction of raw materials
energy consumption at all stages (including transport)
water consumption and pollution
harmful atmospheric emissions, such as those leading to ozone depletion
global warming and acid rain (CO2, NOx and SO2 production)
material performance, durability, repairability and re-usability
waste generation and efficiency of production
human health issues

Format of the Specification

For each of the materials listed below the original sustainability criteria are given, followed by a discussion of the issues which arose during the design and research stages of the programme. Finally, the preferred option is given, with a summary of the justification for its use in terms of environmental, economic and operational criteria.

Additional: Energy Savings

Cunninghams (FM) Limited have carried out the following calculations on the basis of the standard and sustainable specifications. Several assumptions have been made regarding occupancy rates etc., so the figures should be regarded only as a guide. However, they provide a useful measure of the savings made in terms of energy costs by building to the sustainable specification.

 

Normal Specification

(with concrete ground floor and conventional gas boiler)

Floor

Ground

First / Second

Third

Hot Water (KWh/yr)

4750

4750

4750

Heating (KWh/yr)

8437

7616

7837

Boiler Efficiency

1.47

1.47

1.47

Cost (p/KWh)

1.6

1.6

1.6

Cost (/yr)

310

290

295

 

Sustainable Specification

(with timber floor and condensing boiler)

Floor

Ground

First / Second

Third

Hot Water (KWh/yr)

4750

4750

4750

Heating (KWh/yr)

6712

6016

6274

Boiler Efficiency

1.17

1.17

1.17

Cost (p/KWh)

1.6

1.6

1.6

Cost (/yr)

215

205

210

This gives approximate savings for the development as follows:

Annual Energy Cost Savings from Sustainable Specification

(not including electricity savings)

 

Ground

First / Second

Third

Saving (%)

30.6

29.3

28.8

Saving (/flat/yr)

95

85

85

Total saving for development (/yr)

8,300

These figures are indicative only but provide a useful indicator of the purely financial benefits of adopting the sustainable specification in terms of energy savings. They do not take into account any of the other benefits.