This tool allows you to investigate renewable energy strategies for a proposed or existing building. It is designed to interactively explore different options at an early stage in the design process.

A basic configuration of site, building and renewable systems can be chosen using the pull down menus of standard options and the simple entry fields, all of which are shown in pale green. The numerical values used in the estimates are shown in the orange boxes and are updated depending on your choices. If you wish to hone your estimates then you can adjust these values. Each section has an link providing further information. The pane to the right indicates the effect of renewable energy systems on your building's energy consumption, bills, embodied energy and construction cost.

In addition to estimating costs and reductions in primary energy use, the tool allows you to take account of the embodied energy of the renewable systems and of any components which they might replace. Ideally we should also consider the overall effect of the strategy on energy use - does the facade reduce thermal performance leading to higher heating loads? Is the form of the building when the facade is incorporated less easy to naturally light or ventilate? These issues are not tackled as they require far more detailed modelling.

This project was funded by the Cambridge-MIT Institute and carried out by Jonathan Woolf at the Martin Centre for Architectural Research at the University of Cambridge, UK between November 2001 and August 2002.

The amount of wind energy on a site depends not only upon its geographic location but on the surrounding terrain.

sheltered (wooded/urban) open countryside coastal (open countryside) hilltop (open countryside)

Select a building type and floor area below. This gives a baseline energy use, construction cost and embodied energy which are then modified by the addition of renewable energy systems.

naturally ventilated cellular office naturally ventilated open plan office standard air conditioned office prestige air conditioned office with treated floor area m²

Mean horizon angle 0 15 30 50 degrees

user defined clay roof tiles aluminium roofing steel rainscreen cladding double glazed cladding polished stone cladding

Lifetime

years

Embodied energy

kWh / m2

Installed cost

£ / m2

user defined flatplate collectors vacuum tube collectors with area of m²

Mean horizon angle 0 15 30 50 degrees

user defined clay roof tiles aluminium roofing steel rainscreen cladding double glazed cladding polished stone cladding

user defined 2.5m diameter 5.5m diameter 7m diameter 9m diameter 30m diameter 44m diameter 58m diameter 80m diameter rotors in an array with machine(s).

Wind turbines are sensitive to the surrounding terrain and to obstructions to the smooth flow of wind. The higher the turbine the less effected it is and the greater the output. Small turbines should be mounted as high as possible and large turbines usually have a tower roughly as tall as the blade diameter.

Height of the wind turbine hub above ground 10 20 30 40 50 60 70 m

All estimates shown to 2 significant figures.

¹The primary energy consumption of the building. This takes into account the efficiency of conversion of energy at each stage in the process from source to supply. For example, each delivered kilowatt-hour of mains electricity in Britain corresponds to around 3.6 KWh of primary energy (mostly in the form of fossil fuels). Primary energy is a good indicator of carbon dioxide emissions and of other environmental concerns.

²The embodied energy of the building. This takes into account the energy required to manufacture, transport and install all the components of the building. The figure shown is a per year figure divided by lifetime i.e. the embodied energy of each component is divided by its lifetime to provide comparison between components with differing lifespans.

All estimates shown to 2 significant figures.

³Photovoltaic and wind turbine output is shown as a percentage of the building's electricity consumption and solar water heating as a percentage of the energy demand for hot water.

⁴This row shows the contribution of each renewable in reducing the primary energy consumption of the building. Photovoltaics and wind power, which substitute for relatively inefficient electricity generation, have a larger impact per generated unit than solar water heating.

⁵The contribution of each renewable is shown as a percentage of the annual primary energy consumption of the building without any renewable systems.

⁶The embodied energy of each renewable energy system. The figure shown is normalised by lifetime i.e. the total embodied energy is divided by the lifetime in years to allow comparison between systems with different lifetimes.

⁷The embodied energy (divided by lifetime) of any components replaced by either photovoltaics or solar water heating panels is shown in this row.

⁸The net embodied energy is the embodied energy of the renewable components less that of the components they replace, again divided by the respective lifetimes.

⁹The percentage of the lifetime of the renewable system required to generate the associated net embodied energy.

All estimates shown to 2 significant figures.

¹⁰The revenue from each renewable is shown as a percentage of the relevant annual energy bill (i.e. electricity for photovoltaics and wind turbines, and gas or oil for solar water heating) for the building without any renewable contributions.