Reducing energy and water use

Before the refurbishment the building was nearly in its original state in terms of energy conservation (it appears to date from the late 18th century, with a compatible 20th century extension) - the only addition of note being a thin layer of loft insulation.

Other characteristics of the building contributing to particularly high carbon dioxide emissions included uninsulated solid walls, electrical space heating, single glazing and incandescent lighting.

Not all these issues could be addressed within the budget, but very significant progress was made, which will be reflected in future energy bills.

General energy efficiency

High energy efficiency is one of the basics of sustainable buildings. This can be achieved by doing the simple things well and cost-effectively, and by using innovative technologies.

The obvious reasons for energy efficiency include:

• lower energy bills;
• the effect on climate change;
• energy-efficient components and systems reduce unwanted heat gain and the need for artificial cooling;
• the opportunity to showcase technical expertise and commitment.

Other advantages can include:

• more natural daylight and less need for artificial lighting;
• improved air quality efficiently pre-warmed or cooled as required;
• less noise, due to lower mechanical requirements

In refurbishments, the opportunities for achieving high levels of energy efficiency are, to an extent, constrained by the design of the existing building (its shape, structure, orientation and glazing areas, for instance). So use old utility bills to determine the most important areas for improvement.

Effective and appropriate energy efficiency measures quickly repay investment and contribute to long-term savings for both owner and occupier.

How to achieve energy efficiency
Energy efficiency should be at the heart of any refurbishment project, beginning with analysis of the qualities of the building and the site. Achieving best value efficiencies also depends heavily on taking a true partnership approach. By working collaboratively towards an initial concept and design, architects, engineers, landscape designers and space use planners can achieve more than working in traditional hierarchical and compartmentalised teams.

The process of energy efficiency design should always include:

• setting energy targets at an early stage;
• designing to meet user requirements;
• designing for manageability, maintainability, operability and flexibility;
• checking that the final design meets objectives and targets

Computer energy simulation
Computer energy simulations (or Computational Fluid Dynamics - CFD) can be used to ensure that sustainability goals, as well as increasingly complex regulatory requirements, are met. It assesses a building's energy needs throughout the design process and is likely to be relevant in the case of more complex buildings/modifications.

Renewable energy
To reduce energy demand and environmental impact, find a more sustainable supply. You could even generate renewable electricity on site.

More sustainable sources of energy are generally referred to as 'alternative energy' systems. A sub-set of these can be accurately described as 'renewable' because they do not deplete natural resources in use and are fuelled entirely by natural systems such as the sun, wind, waves, biomass etc. The spectrum of alternative energies includes active solar for heating, photovoltaic solar cells for generating electricity, small-scale hydroelectric schemes, anaerobic digestion, biomass such as poplar, willow coppice or wind on and offshore, combined heat and power (CHP), tidal and wave power, fuel cells, geothermal ground-source heat pumps and landfill gas.

Some may not be relevant to the design of a particular building but may form part of establishing green energy purchasing plans.

Insulation
The loft has had a best-practice 300mm (1 foot) layer of sheep's wool insulation added. Insulating the solid walls and solid ground floor was considered, but ruled out on grounds of feasibility and cost: if insulating solid walls, consider whether to insulate on the inside or outside of the building, and what effect this might have in terms of appearance and - if insulated inside - condensation.

Draught proofing
All traditional sliding sash windows were in reasonable condition, and it was agreed that, despite being single glazed, refurbishment was a more sustainable and cost-effective option than replacement. This involved creating slots around the edges of the windows and inserting brushes (completely hidden from view) into them. The result is a dramatic reduction in heat loss and draughts, a more comfortable and natural working environment and the retention of the traditional character of the windows.

Woodchip boiler
Woodchip for fuel, from fast-growing sitka spruce in Scotland, is a small but growing local market and a woodchip boiler can create "carbon neutral" heat. In contrast to burning fossil fuels, the carbon dioxide emissions from burning the fuel merely counterbalance the carbon absorbed from the atmosphere while the wood was growing: thus, if the timber comes from sustainably managed forests, the net contribution to global warming is negligible.

The woodchip boiler has not yet been installed, as we are clarifying whether it fulfils all our requirements, and we await confirmation from the Energy Savings Trust that grant funding is available under the Scottish Community and Household Renewables Initiative.

Daylight strategy
By optimising daylight, a more comfortable working environment and reduced electricity bills for lighting can be achieved. At Dunkeld, this involved capitalising on the existing windows - opening up the internal layout to allow daylight penetration into all offices, and fitting adjustable vertical blinds, which can be used to limit glare whilst impacting little on daylight. Painting the walls and ceilings in light colours (and keeping them clean) also helps.

Energy efficient lighting and controls
The refurbishment included complete rewiring and replacement of the old lighting installation which was unsuitable for offices. The overhead office lighting is provided by highly efficient T5 fluorescent strips: these supply an adequate - but not generous - level of general lighting. This lighting can be topped up locally - as required - by an efficient (compact fluorescent) task light on each desk. Lighting in corridors and kitchens is controlled by infrared sensors, which automatically step down the light intensity during periods of inactivity.

Water

Although excessive water consumption is not usually a major problem in a small office, steps can still be taken to limit mains water use.

At Dunkeld, dual flush WCs were fitted, and rainwater will be collected for watering the garden. Rainwater for WC flushing was evaluated, but rejected on the grounds of cost: this is one of the drawbacks of a leasing arrangement where the occupier has a limited time to recover costs.

Water efficiency
Although the UK is one of the damper parts of the world, it is also densely populated so the demand for water often exceeds what water authorities can supply. This also creates demand for pumping and water treatment, which creates further costs and environmental impact.

There are three overarching facets to water conservation, as is the case with conserving any natural resource. These are:

• Reducing demand;
• Getting supplies from more sustainable sources;and
• Transporting supplies with minimum waste or loss.

The related responsibility for designers of buildings is to specify water efficient taps, WCs and other appliances, and investigate systems for use of rainwater and/or greywater (from showers, basins, washing machines) in place of mains water for some applications.

There are many water saving technologies which can combine to slash water consumption in an existing building.

Technology
Water conservation technologies have been applied to pretty much everything that relates to water use - WCs, urinals, washbasins, plumbing, showers, washing machines, etc. For instance, some give you a good result whilst using less water (water efficient or even water-less features) and others are designed to prevent waste and promote better management (e.g. infrared detectors and water meters).

Water treatment and recovery
Further water savings can be made by capturing, storing, treating and reusing rainwater or greywater for applications such as irrigation and toilet flushing.

It is even possible (although highly unusual) for a development to be completely independent of the water mains and sewerage system - but this requires a sufficient rainwater catchment area and land to host the reedbeds needed for sewage treatment.

Sustainable urban drainage systems (SUDS)
The challenge of developing a sustainable drainage system is to provide development which will not contribute to flooding problems and water pollution. Recommended techniques fall into three primary categories: infiltration systems, permeable conveyance systems and passive treatment systems. Because of SUDS' reliance on natural processes, the opportunities to promote biodiversity and amenity value can be capitalised.