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Planning an energy efficient renovation

Posted by Tim Pullen on 8 November 2010 at 9:35 am

Why is it that people starting renovation projects have "so much to think about it is difficult to know where to start"? I am yet to meet a self-builder undertaking a new build that makes that complaint. Maybe the answer is that renovation is not treated with the same consideration and respect as a new build.

The essential first step is to plan and cost the renovation in the same way as a new build would be. So many renovations start work on the day the property is purchased, with a fixed budget that is simply the amount of money available, regardless of how much is needed.

A YouGen visitor has asked what energy efficiency measures should be considered in the renovation of: An 1840s brick, solid wall construction house. Current heating: a rayburn for hot water plus economy 7 night storage heaters. It’s off mains gas, has a south facing roof, and land which offers potential for wood supply and maybe a wind turbine. The windows are single glazed with rotten frames. Currently no insulation at all. 

To plan properly the renovator first needs to understand how the building was designed to work. For example, does it have breathing walls, where are the air bricks, is there ventilation in the roof space, what are the ‘must-do’s’ (rotten window frames), what are the no-no’s? The fact that this may be more a refurbishment than a renovation does not make the planning and budgeting any less important.

The 5 key steps, in order of priority, are: 

1. Energy conservation

Insulation and draught proofing. This means working out the heat load in the same way as for a new build and planning the insulation and air-tightness to meet the desired consumption figure. This is not as easy as it would be for a new build as the U-values of each element (wall, window, roof, etc.) need to be calculated.

2. Windows & Doors

To replace or not. Replacement double-glazed windows are not necessarily essential and consideration should be given to alternatives. Secondary double-glazing can be more cost effective and give more flexibility. The decision will impact on the overall heat load and will feed back into the calculations.

3. Heating system & controls

A gas or oil boiler over 10 years old will probably need replacing but so will the control system. Good controls that allow the temperature and timing of heat delivery to each room are essential to a good system. In this case the night-storage heaters will have to be replaced (woefully inefficient) and a new distribution system installed as well. 

4. Heating distribution

Radiators, skirting heating or underfloor heating. The decision on this will influence the decision on the primary heat source (oil or gas boiler, heat pump, solar or biomass). Underfloor heating will allow any primary heat source as it operates at very low temperatures. Radiators generally need very high temperature water and essentially exclude heat pumps. Skirting heating can be cheaper and easier to install than underfloor and some (Climaboard) will take low temperature flow. 

5. Renewable energy options

This will relate to the site and the demand from the house. Once all the other issues have been decided on (and the heating system is likely to incorporate some renewable heat technology) the requirement can be calculated more accurately and the budget needed arrived at. 

The 6th step, is to feed all these decisions back into the plan and work out the budget, and maybe go through the whole process again. 

About the author: Tim Pullen is eco-editor for Homebuilding & Renovating magazine, author of Simply Sustainable Homes and founder of sustainable property consultancy WeatherWorks.

If you have a question about anything in the above blog, please ask it in the comments section below.

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1 comments - read them below or add one


gonzo39Comment left on: 24 May 2011 at 10:35 am

Great blog, Im currently in the motions of creating my own home. I am extremely interested in making some energy efficent specifications to my new build planning designs. This has helped me make a few key desicions so once again thank you for you time and effort.

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