Making a home a healthy place to live in, almost always increases comfort levels and energy efficiency at the same time.
There are several requirements to ensure the health and comfort of a building’s occupants and the main ones are set out below followed by an outline of the measures which can be taken to ensure health and comfort levels are met.
1/A constant ambient temperature throughout of about 20° C (68°F) Research has shown that 20° C is the most comfortable ambient temperature for most people. Any temperature variation too far above or below that can be uncomfortable and if severe, can be detrimental to health, especially as one gets older.
2/No perceptible temperature differences Even at around 20°C within a room, a variation of more than 0.8° C (1.44°F) in ambient temperature in different parts of it can be perceived as uncomfortable and shows that humans are very sensitive to temperature.
Two thirds of the heat we feel comes from nearby surface temperatures and not from the ambient air temperature; this is one of the reasons that one can still feel cold in a room with an otherwise acceptable ambient air temperature. Windows and uninsulated exterior walls at a temperature much lower than the ambient air are good examples of elements which can cause this effect.
Even if surface temperatures are not much below ambient air temperature, a difference in temperature between different surfaces of more than 4.2°C (7.6°F) can also feel uncomfortable; likewise, even a small difference in temperature between the top and bottom of ones’ body can induce discomfort.
3/Low internal air movement. High velocities of air movement (otherwise known as draughts) are uncomfortable but especially if in the heating season their source is from outside and is something likely to cause one to turn up the heating to compensate.
4/Good indoor air quality This includes low levels of CO2 and a relative humidity of between 40 & 60% both of which can be provided by good ventilation. In addition, there should be low pollution levels from either internal sources (mould, damp, dust mites etc) or external sources (roads, industry etc).
5/Good natural and artificial lighting It has been shown that the amount, intensity and type of light can affect ones’ physical health and also mood. As one gets older one needs brighter lighting to comfortably achieve certain tasks as the eyes become increasingly inefficient.
6/Physical activity As one gets older one often moves around less and so one can start to feel colder even at an ambient temperature one was content with in the past.
7/ Clothing I think is probably self-explanatory
8/A person’s ability to deal with extremes of heat and cold Unfortunately, physiologically this often becomes less as one gets older.
These then are the main factors which dictate a healthy living environment and whether one feels comfortable or not; though the last three are unlikely to affected by any alterations one can make to a building I have included them for completeness.
Retrofit measures to achieve health & comfort as well as reduced energy costs in an existing building
In an un-refurbished older building it can be difficult to achieve many of the comfort levels described above due to the fact that they often have little or no insulation, large areas of cold surfaces (walls, doors, windows, floors, ceilings), gaps in the fabric causing draughts, large openable windows/fixed open grilles for ventilation and inefficient heating appliances.
As well as making one uncomfortable all of these can cause the loss of large amounts of energy to the ambient air and often the only solution is to turn up the heating to compensate, which in turn uses yet more energy.
Energy saving and therefore health and comfort enhancing measures can broadly be divided into three areas:
1/Reducing heat loss from the fabric of the building This can go a long way to achieving 1/ 2/ 3/ & 4/ in the comfort and health section above and can be broken down as follows:
a/ reducing heat conduction through floors, walls, windows/doors and roofs by adding insulation. Heat will always flow from a hot element to a cooler one and all insulation does is to reduce the rate at which this process happens.
Unless major refurbishment works are planned or access to a structural element is relatively easy, such as loft space or cavity wall, installing insulation to walls and floors can be more difficult to carry out well in existing buildings.
Installing exterior insulation is generally easier and done well is likely to be more effective as many thermal bridges (an unbroken solid route through which heat can flow from inside to out, such as a window frame) can be broken.
Installing interior insulation is often disruptive, can be more complicated and runs the risk of reducing room sizes; however, there are instances where there is no alternative because the exterior is listed or a particular façade which needs preserving.
Insulation is best carried out to a consistent depth throughout the building to both gain maximum effect from the insulation and also to avoid cold spots where damage may be caused to the building’s structure through condensation inside the structure (interstitial) in addition to making the occupants uncomfortable.
b/preventing uncontrolled ventilation – any air which doesn’t enter or exit a building through something controllable such as a window is uncontrolled ventilation. The many gaps in the building fabric of older buildings such as under doors, unsealed windows, ventilation grilles, air permeable materials etc combine to allow lots of heat to be lost.
A good indication of uncontrolled ventilation is being able to feel a draught when all windows and doors are shut. In the heating season if you can feel a cold draught then a corresponding volume of expensively heated air will be escaping somewhere else.
To prevent uncontrolled ventilation, the goal is to install an un-punctured air-tightness layer surrounding the whole building so that no air can come in or out except by controlled means.
This is more difficult to install in an existing building and so it often comes down to treating easily accessible areas such as windows/doors, window & door/frame junctions, chimneys, loft hatches etc. Less easy to treat hidden areas are floor/wall/roof junctions and air permeable building materials.
About 25% of heat energy is lost due to uncontrolled ventilation from an average house (as opposed to through conduction through and radiation from the building structure) however as one increases insulation levels this percentage increases so it is important that insulation and air-tightness measures are carried out together.
A reasonable level of airtightness is often achievable in an existing building just by resolving problems in the easy to treat areas, however once one has achieved something approaching an airtight envelope, effective controlled ventilation is required to supply oxygen and remove CO2 and moisture created by occupants.
When installing insulation/airtightness measures it is vital that they are designed and installed properly as if they are not there is a strong possibility of damage to the building’s internal structure over time from condensation, especially if it is made of wood.
c/ ensuring controlled ventilation - opening windows/doors is generally a blunt instrument for controlling ventilation and often either too much or too little air will flow as natural ventilation is dependent on the size of aperture and the availability and speed of the wind outside. In addition in the heating season opening windows allows expensively heated air to escape outside and in summer it allows warm air in which can add to discomfort.
In contrast a Mechanical Ventilation Heat Recovery system (MVHR) through terminals in the ceiling, extracts damp air from bathrooms and kitchens and taking heat from that air on its way out then gives it back to the incoming cool air before it is piped into the living and bedrooms through ceiling vents to provide ventilation.
A properly designed and set up system will extract 95% of the heat from the air being extracted from the wet rooms which provides excellent air quality and has very low air movement (i.e you won’t be able to feel it even standing under one of terminals); it will also be all but inaudible even in a bedroom at night. As such MVHR provides controlled and energy efficient ventilation.
For MVHR to work properly however, the building in question has to be made airtight and if one is going to install airtightness measures one needs to install insulation as well. This can add to the cost of installation so it is only really worth installing MVHR as part of a more comprehensive refurbishment to achieve the comfort/energy saving measures outlined above.
A halfway house between windows and MVHR is Mechanical Extract Ventilation (MEV) which works on the same principle but only extracts and does not supply; the supply air comes through gaps in the buildings fabric. This form of ventilation is controllable and thus more energy efficient and comfortable than window based ventilation as it removes the likelihood of draughts from that source.
2/Reducing metered energy usage through the use of energy efficient gas/electrical appliances and lighting along with effective controls. Hot water pipes should also be insulated to prevent heat loss.
3/Installing renewable energy technologies such as solar thermal, solar photovoltaic, heat pumps, biomass etc.
Richard can help with all everything outlined above so please click below on one of the numbers below or the email address to contact him.