On average, UK mains electricity produces much lower CO2 emissions per delivered unit now than it did in 1990 and before owing to higher efficiency, a more significant proportion of gas-fired generation and higher availability of nuclear plant. However, burning fossil fuels at a conversion efficiency of between 30% and 60% still accounts for about 70% of UK production, therefore, to use electricity directly for heating (and for hot water in any quantity) can be considerably more polluting than using fossil fuels.
Renewable energy sources have close to zero CO2 emissions, it is evident for direct generators such as wind power, hydro-electric generation, etc. It also applies when burning biomass such as straw and woodchip, apart from any fossil fuel used in cultivation, harvesting, transport, and drying. The carbon dioxide produced by burning the woodchips is taken back up in the cycle if the coppice sourcing the woodchips is allowed to re-grow. Effectively, one has net zero CO2 emissions, where energy from the sun is collected and harvested as a storable fuel source with minimal fossil fuel use.
Materials should be selected carefully and specified to ensure that they cause as little pollution as possible throughout their life: during extraction; in manufacture; during construction or installation; when performing their intended use; and when finally removed for re-use, recycling or disposal. Increasingly, the determiner must be aware of the life cost and impact of each material specified, it embraces the environmental and health implications throughout its life and uses including toxicity and the presence of dioxins and volatile organic compounds (VOCs). Only if a careful holistic approach to design is adopted, the risks to health and the environment will be reduced and genuinely sustainable solutions formulated. Views on specific materials can change rapidly, for example, many countries are becoming concerned about the use of polyvinyl chloride, owing to its perceived threats to environment and health, particularly during manufacture and if it is burned at the end of its life cycle.
4.1.2 Material Selection
Some traditional materials and many modern synthetic materials can be deleterious to inside air quality. Risks can occur during and directly after application of the element when concentrations of associated pollutants are highest, or over a prolonged extend of time. There is often scientific uncertainty over the risk posed to humans. It is due to a large number of chemicals exist in the inside environment. There are 75,000 chemicals in common commercial, only 4% of them have been tested for carcinogenicity (27). In the 20th Century, 50 materials were used in houses. Now there are 55,000 house materials, and half are manmade (28).
Where there is scientific uncertainty about the safety of material and credible evidence to determine, it has the potential to put a risk on the environment and human health, the precautionary principle can be adopted. It means that scientific uncertainty should not come in the method of presenting measures to support the quality of the inside environment, for instance, many chemicals particle have been discovered to be animal carcinogens, but about establishing as a chemical particle is a carcinogen of human can be difficult to obtain. In addition, humans are exposed to some different chemicals in their daily life and identifying causative effects of one chemical can be challenging. So, it is wise to practice a caution in the context of uncertainty.
Many materials have a deleterious put health risks throughout their life cycle and impact on the environment (29). There is an improved awareness about the influence of chemical toxicity, some of it has been reflected in best practice policy and guidance as well as legislation. Berge (2000), Curwell (1986), and Liddell (2007) suggest the issue further. It contains recycled and re-use materials, the usage of those may not be a positive activity on the environment because of embodied toxicity. As there are no mechanisms to vet the toxicity of recycled materials in place yet, and the responsibility lies with the contractor or designer, house owners need to consider the future liability for disposal of a toxic substance.
4.1.3 Traditional house Materials
The selection of appropriate materials for use in traditional houses is a priority. During the renovation, it is paramount to have a full understanding of the properties of the elements being used and the function of elements being replaced. Traditional materials may not be displaceable immediately with modern elements. Several of the materials used in traditional houses are hygroscopic (meaning that they readily absorb moisture), and wall constructions are moisture transfusive (they allow moisture to pass through their fabric), these permitted traditional buildings to deal with moisture by a combination of absorption and evaporation.
It is vital that any materials selected do not compromise the ability of the building to deal with moisture. Maintaining the vapour permeability of traditional materials can be an essential factor in maintaining a healthy indoor environment in conventional structures. Permeability will be undermined with the application of impervious finishes, also several modern finishes and materials are impermeable. Applying such finishes and materials to traditional houses can compromise the ability of the house to deal with humidity and leading to problems linked with high relative moisture, including mould growth, and in several cases resulting in significant damage to the fabric of the house. Furthermore, studies have shown that elements with hygroscopic properties can be used as moisture buffers to reduce the extremes of internal relative humidity. For example, lime is one of the essential non-metallic minerals used in the house construction industry, and its usage in houses dates back to the Neolithic Period. Lime extensively used both externally and internally in traditional houses in Scotland. Lime plaster is being used increasingly as an interior surface finish due to its hygroscopicity, it is known that mould will not grow when the level of PH is higher than 6.0, and because the lime is alkaline, it has been used historically to protect against mould or fungal growth. Nevertheless, there is a lack of scientific information to back these claims.
4.1.2 Efficient system
Upgrading the energy efficiency of the fabric of a historic house can often be difficult, so it becomes particularly necessary to make the installed plant and systems as efficient as possible, even if they cost more. The main areas of concern are a boiler and air-conditioning plant efficiency and control, and any electric motors which run for extended periods. Fossil fuel boilers should be at the top of the available efficiency range. It will usually mean condensing boilers, and these have been used successfully in many of the case studies. However, condensing boilers create a much larger visible plume of water vapor at the flue terminal or chimney top than do conventional boilers. Flues must, therefore, discharge away from areas susceptible to a build-up of moisture. Where It is impossible (e.g., in a small courtyard), a noncondensing model may be necessary. It is also necessary to provide a drain for the products of condensation which can be acidic.
It is essential to compare boiler efficiency not just at the full output but across the possible performing range, e.g., at high and low firing. For domestic sized boilers, seasonal efficiency can be checked through the Sedbuk rating (see www.boilers.org.uk). Boilers in category A would be appropriate, especially in houses where insulation measures are not practicable.
Air-conditioning plant can have a significant physical impact and use much energy. It should only be installed where it is proven to be essential to the operation of the house. Systems which default to on unnecessarily and wastefully are all-too-common in houses today, so controls should be designed and commissioned to ensure that plant is only operated when and to the extent it is needed. When selecting electric motors, calculate how much they will run. If it is more than 1500 hours per year, assess the economics of installing either high-efficiency or DC types.
Combining heat and power (CHP) is a method of maximising the amount of energy from the fuel, so reducing carbon dioxide emissions. CHP both produces power (usually as electricity, but sometimes as mechanical power), and makes available much of the otherwise wasted heat from this process. It can be used to provide heating or hot water or to run equipment, e.g., absorption chillers. It is important to consider that there are sufficient base loads of both heat and power to make the CHP plant run for enough time to produce a reasonable economic case for investment (typically at least 3500 hours per year, as often occurs in hospitals and large hotels). The big mistakes often made are to oversize the plant, or to assume that the heat is free. CHP is very unlikely to be viable without a guaranteed year-round use for the heat.
4.1.3 Low water use
Where new water appliances are installed, consider water- efficient types, e.g., low-flush (less than 6 liters) and dual-flush (two-button) WCs, hand basins with automatic spray taps using less than 2 l/min, low water showers (less than 8 l/min), and waterless WCs and urinals. Equipment found in older houses can often be very extravagant, but its performance can sometimes be improved considerably, e.g., by fitting flow restrictors to taps. Convoluted hot-water supply and distribution systems can waste much heat, particularly if uninsulated and in more substantial houses, seek opportunities to rationalize and improve them. Sometimes, a decentralized system with local gas or even electric water heaters will be more economical and energy efficient.
Water leaks are a serious threat, with risks ranging from significant flooding to slow drips causing staining and eventually perhaps dry rot. Problems can be reduced by careful routing, proper specification using burst-resistant materials, excellent workmanship, inspection, testing, and effective frost protection. In sensitive situations, one can install safety guttering or electronic leak detection systems; or, for significant leaks, automatic alarms and shut-offs. Sometimes, it will be best to keep water out of an area altogether.
4.2 Re-using existing services
Existing house services plant must regularly be assessed to determine whether it is working correctly, its efficiency, safety, life expectancy and any risks it poses. Many types of services, particularly heat emitters and lighting equipment, are often suitable for re-use and add considerably to the character of a house. Such equipment must be checked thoroughly and upgraded as necessary. It is often possible to restore old light switches and luminaires and make them safe. Old radiators will require cleaning and pressure-testing, and the joints and valves should be checked, eased and renewed as necessary.
If pipework is to be re-used, the water should be tested, and external and internal inspections of the pipework should be carried out. Chemical cleaning may also be required. Before it is recommissioned, the entire system should be sufficiently pressure tested in operation, and thoroughly checked for leaks and other faults.
Assess health risks associated with the use of the existing house services equipment can determine how to handle them and whether the plant can be re-used. Dangerous and health-threatening services should not, of course, be retained in use, the health and safety of the occupants must have priority. Dangerous electrical installations and equipment must always be made safe immediately. Fire is one of the greatest threats to the fabric and contents of historic houses (30) (31).
Asbestos was very widely used to lag boilers and pipework. If it is encountered or even thought to exist, it is essential to leave it alone and seek specialist advice. Licensed contractors must be employed to remove and dispose of any asbestos.
4.2.1 Temporary services
Temporary services, particularly those used during construction work (e.g., transformers, cables, lighting, heaters, and dehumidifiers), can create hazards of their own. People may bring in their conventional equipment or misuse it, without thinking about the sensitivity of the house. Risks include not only fire, electric shock and oil spills from generators, but also damage to the historic fabric by too vigorous use of heaters and dehumidifiers. Rapid decreases in humidity can cause shrinkage and crack, particularly in timber products.
Where temporary heaters and dehumidifiers are used, vulnerable contents will need to be taken into safe storage, and vulnerable house elements protected. Alternatively, these temporary systems may need to be operated under the supervision of a conservator. On the other hand, dehumidifiers can often be ineffective because the space to be dried is not correctly sealed, with doors, flues, and holes remaining open. Since water is collected, people think that the dehumidifier is doing its job; whereas most of the moisture has come from elsewhere, often directly from the outdoor air.
4.3 Criteria for the selection of new services in historic houses
Exposing a historic house to unnecessary change increases the potential for irreparable damage. If it is essential to proceed, the new or upgraded services must be, compatible with the house; compatible with the performance of the fabric; and efficient, to minimise the impact on the environment.
Where existing house services are retained, it is essential to ensure that the new services are integrated successfully in a manner that does not compromise installation, performance, use, efficiency, maintenance or life expectancy. For example, old heating systems often came up to temperature slowly, and the thermal shock from the faster response of modern boiler plant might give rise to leaks in existing pipework. Similarly, more compact, higher-resistance modern terminal devices requiring high water pressures may not mix on the same circuit as old radiators designed for gravity flow.
4.3.1 Installing new services and upgrading existing ones
Finding suitable routes for pipes, cables, and ductwork needs careful thought and imagination to minimise interventions, and to avoid other problems for the fabric or, at worst, structural stability. In modern houses, house services are often not designed or specified in detail; much is left to the discretion of the contractor, for example, the cable runs between switches and luminaires are very seldom shown. In many historic houses, such detailed design is essential to improve planning and appearance, and to minimise unnecessary physical intervention. The further investigations, drawings, specifications and collaboration on site will inevitably add to the time and costs.
220.127.116.11 Notching, cutting and chasing
Work to accommodate services can seriously affect the condition, structural performance, and preservation of older houses, and should only be carried out after appropriate specialist advice has been sought. A good starting point is to aim not to notch or cut any timbers, chase any walls, or make holes in prominent places. Cutting and chasing destroy historic fabric, may be unsightly and can severely weaken floors and old walls and partitions. Floorboards and wall finishes of historical, architectural or archaeological interest could be damaged irreparably or even lost.
Where the covering surfaces (e.g., floorboards) can be removed safely and carefully (with the approval of the relevant officials), opening-up often reveals hidden opportunities for service runs (and sometimes even equipment), together with unexpected obstacles. A good set of drawings also reveals possibilities for vertical connections. Thick walls may also contain useful voids, in Sample ….
Opening-up can also reveal horrors, e.g., decay, unexpected obstacles, and structure irresponsibly cut away by those installing previous house services installations. Strengthening will then be required. Ways to strengthen weakened floor timbers, for example by using folding wedges or iron plates are shown in BS 5268 (32).
18.104.22.168 Installing service runs
The first stage is to minimise the amount of pipework, cabling and ducting needed, together with any intervention to the existing fabric. Case study 24 illustrates why fan-coil air conditioning was chosen in preference to an all-air system at the Royal Society of Chemistry. The house services engineer must work closely with the architect or surveyor (and then the builder) to minimise, and where possible avoid, situations that cause physical damage, surface damage or removal of any part of the structure and fabric. Any alterations to the drawn and agreed scheme should also be confirmed on site before any physical work commences.
Regards to the mortar and masonry materials, provided that the mortar is high enough, it is better to secure fixings in the mortar than in masonry. It provides a degree of reversibility and prevents damage to masonry, which is more difficult and expensive to replace. Also, about timbers and plaster, where a large number of securing points is required, a separate fixing plate will provide a suitable surface and reduce the number of fixings to the historic fabric.
4.3.2 Exposed services
Use of exposed pipes, cableways and sometimes ducts can minimise the amount of physical damage and intervention to historic fabric. In a formal room with excellent detailing, exposed runs are unlikely to be appropriate as they would detract from the original attention to detail and geometry. Unoccupied areas, attic spaces, cellars, roof spaces and other areas where appearance or presentation is less of an issue create excellent opportunities for exposed service runs and less concern about their appearance. Exposing services can also be more reversible and improve access to inspection, alteration and maintenance, and eventual removal and renewal.
Exposed pipework and ductwork need to be insulated, and frost-protection strategies must be taken very seriously; for example, what should be the design strategy for a house which could be empty and difficult to reach during an extended cold period, as in case study 13.
Where cables are run exposed, they must be carefully positioned, specified or protected to minimise their vulnerability to physical damage. Cabling in historic houses may also need to exceed minimum requirements, to reduce fire risks; and mineral insulated cables (MIC) or other specialist cable types may be appropriate. Although specialist cabling can be more expensive, it has the benefit of minimising the use of polyvinyl chloride, can last longer and may need fewer fixings and supports.
Where installation of cable runs is likely to be extremely difficult or damaging, radio and signal receptive systems can be considered — see case studies 19 and 25. These look promising, but their long-term performance and their potential influence on health are currently unknown. The radio devices in inaccessible locations without mains supplies still need regular access to change the batteries, typically every few years, but sometimes more frequently.
4.3.3 Concealed pipework
Older houses often have voids and other spaces that can be used to conceal pipework and other services and to limit any damage to the historic fabric. The alternative options have been listed in Figure 5.