Gallery
Modern house-building has become increasingly complex with homes being tasked to achieve more and more, whether that be energy efficiency performance, adaptable living spaces or aesthetics. These considerations are even more important to the self-builder as the project becomes personal and often represents a ‘forever home’ situation. In these instances, fenestration choice is crucial as not only will it have a huge impact on the external appearance of the property, it will also affect the building’s performance and comfort.
The first and most basic consideration is style and this will largely be dictated by the material choice. Timber is often preferred for traditional and country-style properties and is seen as an aspirational choice because of its classic visual appeal and warm texture. It has great durability and is very versatile. Timber also offers exceptional performance.
A little known fact about timber is that it is widely recognised as one of the most efficient natural insulators available and when this is combined with modern glazing technology, timber windows and doors can perform even better than they look. The Andersen ‘A’ Series double glazed casement window, for example, delivers impressive energy efficiency ratings, with a U-value of just 1.4 W/m²K and this drops to a staggering 0.93 W/m²K in the triple glazed units.
Timber fenestration can also lend itself to modern refurbishments of period buildings with the option of dual finish products – that is, a unit with a different interior style to that of the exterior. This way, the fenestration can blend into local architecture on the outside, but provide an individual style on the interior.
High specification
For completely contemporary properties, aluminium products are a great fit, but it’s worth highlighting that high specification options are always best to guarantee the longevity of the units. Aluminium, as well as timber, is a very sustainable choice and can be easily recycled. What’s more, aluminium windows and doors are easily manufactured into huge bespoke shapes and sizes, whilst retaining their strength, making them a versatile option.
The other key consideration when choosing fenestration is thermal efficiency. With some figures estimating that as much as 25% of a home’s heat loss is through its windows and doors, choosing efficient units is essential to the long-term performance of a home. Put simply, two options then present themselves to self-builders: either keep the number of windows and doors to a minimum, or use highly thermal efficient units.
Whilst restricting the quantity of fenestration may seem like a money saving idea, it is worth bearing in mind that a good portion of the money saved on heating will go into additional artificial lighting instead. Reducing the amount of natural daylight entering a property can have other negative impacts too, as exposure to natural daylight can actually improve health, mood and social interactions making for a much more enjoyable environment – it can even kill bacteria in buildings helping them stay clean.
The good news is that highly thermal efficient units are readily available and because of advances in modern fenestration technology large expanses of glazing can be easily integrated into super-efficient home designs with no risk to performance integrity. What’s more, modern windows and doors are now capable of being used architecturally as well as functionally because of their strength, opening up new and exciting design possibilities. For self-builders, a wall of glass needn’t be a pipe dream anymore, as it is now both structurally and thermally viable. However this is dependent on the U-value achieved by the unit in question.
A U-value is a measure of heat loss and it’s what the fenestration industry uses to grade the thermal efficiency of different units. It is quoted in W/m²K, which shows the amount of heat lost in watts (W) per square metre of material when the temperature (K) outside is at least one degree lower than inside. It may sound complicated but in simple terms, the lower the value the better as this means it will lose less heat. As a benchmark, a good U-value to look out for would be no higher than 1.5 W/m²K for high-quality double glazed units, or below 1.0 W/m²K with triple glazed units.
In particular relation to the comfort of a home, glazing choices become even more important. If fenestration units with high U-values are installed in a property, then cold zones will form in areas around the windows and doors causing draughts. This can become particularly uncomfortable in the winter months. If you were to take a house, for example, that is being heated to maintain an internal temperature of 21°C, when the outside temperature dropped below zero you could expect surface temperatures on various types of glazing as follows: 1°C on single glazed windows, 16°C on modern double glazed windows and 18°C on triple glazed windows. The difference is clear to see and shows how significant convection draughts will form if poor quality units and glazing is used.
Choosing the right windows and doors is crucial not just to the aesthetics, but to the long-term performance and liveability of a home, and thanks to modern technology, fenestration no longer needs to be the thermal weak point. At Black Millwork we provide high-quality products and have years of experience in helping self-builders achieve the results they want.
