With rising costs of energy and the understandable desire of residents to be warm and comfortable in the home, attention will turn each winter to heat loss and how to remedy it. A well insulated home will allow a comfortable ambient temperature to be achieved with the heating on less often and at a lower level, as it will not need to counteract draughts, cold spots and building materials that easily give up your heat. The biggest culprits for heat loss are the roof and windows of a property, and after insulating your loft or roofspace, the choice of how best to insulate the windows is more tricky. It is not just weighing up the alternatives, but how they will look and impact on your personal living space.
Secondary Glazing vs Alternatives
The first consideration is usually to fit Triple or Double Glazing, a familiar enough product that is required in most new residential properties. It can be smart, easy to operate and effective at retaining heat. Many systems incorporate useful features such as trickle ventilation, to combat condensation and security locks. But it is far from being an automatic choice, as it can be hugely expensive, disruptive and messy when it is retrofitted (and all existing windows are completely removed), and the sealed units are prone to failure, needing complete replacement. In conservation areas and in listed buildings, of course, keeping the original windows might be a local authority requirement, and for those in rented accommodation, Secondary Glazing is a more more obvious option.
The best alternative to Double Glazing is Secondary Glazing, which has its critics and its supporters. The immediate and substantial benefit of lower cost can lead to an assumption that it will look "cheap", but this will depend on what system is chosen and how skilfully it is installed - a good secondary glazing system will be inconspicuous and not detract from original features in a house, such as sash, stained glass or leaded windows. Installing Secondary Glazing is a reversible process and can offer significant choice with bespoke fitted panels or DIY systems, which can have screwed, adhesive and magnetic fixings; opening, sliding or fixed panels which can even in some circumstances be fitted on the exterior of the windows. There are pitfalls however, as Secondary Glazing is at the mercy of protruding fittings, uneven window surrounds and distorted window cavities, and a poorly chosen or poorly installed system is unlikely to please.
What else is available? Thick curtains, lined thermal curtains, blinds with heat reflective surfaces or air pockets and shutters all have their part to play, although they will block the light into a room and the view out of it. These alternatives are perhaps best used as nighttime solutions, and also in combination with Secondary Glazing. Other heat retentive measures will include underfloor or floorboard insulation, draught excluders for the doors and letterboxes, without forgetting the existing windows themselves. Should your old windows be too difficult to draught proof effectively, Secondary Glazing will provide an immediate insulating barrier.
The idea of combining different solutions is a common one, and it is not unusual for Secondary Glazing to be fitted to existing Double Glazed windows, as an extra means of saving heat and preventing noise. This can be more effective than Triple Glazing, and Secondary Glazing over a single glazed window can be more effective than Double Glazing. Easyfix Secondary Glazing and Heat Retention.
In researching this page, we looked at many documents and discussions about the effectiveness of different window insulation methods. Leaving preferences aside, the concensus appeared to be that for a single glazed window, Secondary Glazing and Double Glazing should both prevent around 60% of window heat loss. Shutters, blinds, thermal curtains and normal thick curtains (in this order) can still prevent 50% - 20% of heat loss, but they remove all light in the process. The keys for Secondary Glazing seem to be the accurate installation of the product and whether it achieves a thermal seal. If the person fitting it gets this right, then Secondary Glazing is a winning solution - and with Easyfix systems, they are designed so that even a modest DIYer can fit them successfully, using the videos and instructions that are available.