REFURBISHMENT OPTIONS

 Basic

■ Provide heating controls

■ Install electric heating

Good

■ Install centralised heating

 Exemplary

■ Use solar collectors for DHW

■ Use Biomass CHP

Heating controls

A good heating control system for individual flats is essential for good thermal comfort and energy efficiency in a tower block particularly in buildings that have a centralised heating system.

The controls regulate the temperature inside the room by regulating the flow of hot water and the heating demand in the boilers.

The following control systems are recommended for a centralised heating system in tower blocks:

• Thermostatic radiator control valves (TRVs): these allow control of individual radiators. The system is particularly useful in room facing south, where the heating can be turned down or up depending on the passive solar gains.

   

• Electronic room thermostats: It is recommended that manual thermostat timer controls , if present are replaced with electronic programmable ones. This allows heating to be at different temperatures at different times of the day. They can also provide automatic weather compensation which help optimise heating depending on the outdoor temperature.

• Hydraulic Interface Unit: This control is to be used for a  centralised heating system. It replaces individual boilers in flats. It provides control of hot water consumption from the 'mains' in each flat.

Benefits

• Good individual control

• Thermal comfort

• Energy and CO2 reduction

□  TRVs: £30-£40 per radiator

□  Electronic room thermostats: £80-£110/flat

□  Energy Savings Trust

□  Affordable Warmth

Also see:

□  Centralised heating

More information:

□  Natenergy: A Simple Guide to Central Heating Controls

□  Energy Saving Trust - Heating controls

Suppliers:

□  Honeywell UK

□  Danfoss Randall Ltd

To register as a supplier click here...

Centralised heating system

Supply of gas to individual flats for heating is not recommended as the potential impact of a small fault can be colossal in a tower block.  Centralised boilers with hot water supplied to each flat is ideal in tower blocks with elderly tenants, as they tend to use the flat during the day and require a higher temperature for comfort.

Any existing ‘wet’ heating system with individual boilers in each flat can potentially be converted to a district heating. When carefully considered it can improve the efficiency and reduce energy bills.

The heat can be provided from a variety of sources, including;

• Solar thermal

• Geothermal

• Cogeneration plants [CHP]

• Waste heat from industry,

• Purpose-built heating plants with either oil, gas,  biomass or municipal waste.

A combined system can also be installed e.g., gas fired boilers and solar thermal. This is especially relevant whilst using renewable energy systems.

Other considerations

Boiler plant location

The location of the boiler plant needs to be coordinated with other issues and requirements. For example, if locating on the roof or ground floor, the loss of area for social amenities needs to be considered. Locating the plant room away from the building may be a favorable option if space is available.

Heat meters

Heat meters enable the measurement of individual consumption of thermal energy. Heat meters can be used in conjunction with prepayment systems, allowing residents to pay for heat on an actual consumption basis rather than paying a flat rate heating charge.

District heating

Whilst considering a centralised heating option, a feasibility could be carried out to check the potential to provide heating to a wider community [other buildings]. This could help in achieving higher efficiency [economies of scale] and generate additional income for the management from the sale of heat [and electricity in the case of a CHP plant].

Pipe insulation

Whilst considering the use of existing plumbing for the distribution of heat from a centralised plant, insulation of the pipes must be carried out. This will help reduce heat loss and energy consumption.

Heating communal areas

Consider background heating to communal areas such as stairs, floor and entrance lobbies. This will improve thermal comfort, sense of being and create a buffer zone to reduce heat loss from flats to common areas.

Timer controls

Consider using time based controls to shut down DHW recirculation pumps during late nights [2am-5am] when there is low demand.

Benefits

• Centralised heating in tower blocks is one of the most efficient ways to provide space heating.

• Lower carbon dioxide emissions and energy costs.

• Reduce space required in each flat.

• Lower whole life costs compared to individual boilers.

• Potential to combined with alternative heat sources in future.

□  Heat meters: £1300-3000/flat [depending on the pipe size]

□  Central heating system: £50-£65/m2

□  Energy Savings Trust

□  Affordable Warmth

Also see:

□  Heating controls

□  Micro CHP

More information:

□  EST: Community Heating and CHP

Suppliers:

□  Micronics -Heat meter

To register as a supplier click here...

Install solar collectors

Solar collectors can  provide heat for space heating or/and domestic hot water requirements [DHW] when used in conjunction with a conventional heating system.

There are two common types of solar collectors applicable for water heating i.e., flat plate and vacuum tube collectors. 

Flat plate collectors: The flat plate collectors consist of a box with a transparent cover that faces the sun. Metal pipes carrying a heat exchange fluid run through the box which gets heated. The pipes are attached to an absorber plate, which is painted black to absorb the heat. As heat builds up in the collector, it heats the fluid passing through the tubes.

Vacuum tube collectors: These are similar to the flat plate ones but have the absorber plate for collecting sunlight in a vacuum-sealed tube. The thermal losses are very low even in cold climates.
 

Case study: Brandaris Building, Zaandam, Holland   A good example of centralised solar thermal heating in a multi storey building is the 14 storey Brandaris Building in Zaandam, Holland, which has 384 apartments.   In this project the solar thermal system provides at least 15% of the total energy demand for both DHW and space heating using a 760 m2 of flat-plate solar collector panels.

In the UK, about 60% of the energy required for domestic hot water requirement can be met using solar collectors. Typically, each flat would need an approximate area of 2m².

Other considerations

Roof area

The small roof to floor area ratio limits the possibility of solar thermal collectors meeting the buildings heating demand. However, collectors could be considered if space is available around the building. Or alternatively, the solar collectors could be used solely for domestic hot water requirements. Solar collectors on the roof of a typical 20 storey tower block should be able to cater for the DHW load for most flats in the building.

Benefits

• Health and well beings

• Reduced energy cost

• Reduced CO2 emissions

□  £2000/flat for DHW [excluding plumbing costs]

Also see:

□ 

More information:

□  Intermediate Technology Development Group

Suppliers:

□  Sandler FW thermal system

To register as a supplier click here...

Combined heating and power

Combined heating and power [CHP] plant is an installation where there is simultaneous generation of usable heat and  electricity in a single process.

Generation of electricity in fossil fuel [e.g., coal-fired] power stations generates a large quantity of waste heat. Similarly, when electricity is generated on site, the heat releases as a byproduct is tapped to provide space heating and DHW.

The primary fuel for a CHP plant can be provided from a variety of sources, including;

• Fossil fuels [Natural Gas, LPG, Oil, Diesel]

• Fuels cells [Hydrogen]

• Organic fuels [wood pellets, municipal waste]

In order to achieve optimum payback, a  CHP plant is normally sized to meet the peak heat load in summer. The remaining heat is provided by a top-up boiler plant.

However, a larger plant may be feasible, if 'excess' heat and/or electricity can be sold to other buildings such as, schools, hospitals, retail complex and office buildings. This could help in achieving higher efficiency and generate additional income for sale from heat and/or electricity.

Other considerations

Emissions

The components of the exhaust gases, which are of concern because they are hazardous, are the following:

• carbon dioxide (CO2),

• carbon monoxide (CO),

• nitrogen oxides (NOx),

• sulfur dioxides ( SO2),

• unburned hydrocarbons (CxHy, HC or UHC),

• solid particles, called also “particulates”.

An appropriate method of disposing these gases must be given due consideration.

Micro CHP

Micro-CHP units are small enough to meet the heat demand of a household and are typically similar in size to a conventional boiler. Where centralised systems are not feasible micro CHP unit could be considered.

Benefits

• CHP typically achieves a 35% reduction in energy usage and compared with power stations and heat only boilers.

• This is equivalent to a reduction of over 30%in CO2 emissions in comparison with generation from coal-fired power stations, and over 10% in comparison with gas boiler. [Source: CHPA].

□  CHP cost: £65-£80/m2 [note costs are highly variable and dependent on number of flats]

Also see:

□  Centralised heating

More information:

□  EST: Community Heating and CHP

□  CHPA

Suppliers:

□  Vital Energi

□  Powergen's WhisperGen

□  EC power

To register as a supplier click here...

Electric heating

Electric heating is a popular option in multi storey housing. The main drivers for its installation are low capital cost, convenience and safety.

Electric heating is more expensive to run and compared to gas centralised heating pollutes more carbon dioxide. 

• Electrcity-0.5kgCO2/kWh

• Gas-0.2kgCO2/kWh

Therefore, It must only be used if:

• The central heating pipe work to individual flats is difficult to install and;

• the external facade is well insulated and the heat loss through infiltration is reduced substantially [e.g., meets the current Part L2 requirements] and heat recovery ventilation has been installed or;

• the building is occupied mainly by working professionals, who tend to stay away during the day [e.g., 8am-6pm] time.

There are four main types of electric heating system

• Electric panel [radiators]

• Warm air [fan heaters]

• Electric underfloor

• Storage heaters [economy-7]

Storage heater must be the first choice as they are less expensive since they draw electricity during off peak times [night].

Benefits

• The main drivers for its installation are low capital cost, ease of installation, user convenience and safety.

□  £120-£300 per radiator

Also see:

□  Centralised heating

□  Micro CHP

More information:

□  www.natenergy.org.uk

Suppliers:

□  n/a

To register as a supplier click here...