Passivhaus Characteristics

Energy and Water Saving Solutions

There are many differing add-ons to your Integrity built Passivhaus, the following are just a few of the additions that can be added to your home or building.

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Ground Source Heat Pump

An opportunity exists, although not essential with a Passivhaus, to increase the efficiency of the ventilation systems using a ground source heat exchanger. The ground during winter has a higher temperature than outside air and during the summer a lower temperature than outside air. Therefore, it is possible to preheat fresh air in winter and cool it in summer, by utilising a buried earth duct. This is commonly done with brine circulating in earth buried pipes providing geothermal energy and then either heating or cooling the air with a water to air heat exchanger.

A ground source heat pump can be a highly efficient form of space heater, particularly where deployed in conjunction with a low energy heating system such as a ventilation system or under floor heating.

The length of the ground loop depends on the size of your home or building and the amount of heat required. Longer loops can draw more heat from the ground, but need more space to be buried in. If space is limited, a vertical borehole can be drilled instead. Normally the loop is laid flat in wide trenches about two metres deep, but if space is limited, a vertical borehole can be drilled instead containing a vertical loop. Some companies will suggest a using narrow trench which requires less area – we would not recommend this option

Ground source heat pumps (also known as GSHPs) benefits include:
• could lower your fuel bills, especially if you replace conventional electric heating
• could provide you with an income through the government’s Renewable Heat Incentive (RHI)
• could lower your home’s carbon emissions,
• can heat your home and provide hot water
• needs little maintenance – they’re called ‘fit and forget’ technology.

Heat from the ground is absorbed at low temperatures into a fluid inside a loop of pipe (a ground loop) buried underground. The fluid then passes through a compressor that raises it to a higher temperature, which can then heat water for the heating and hot water circuits of the house. The cooled ground-loop fluid passes back into the ground where it absorbs further energy from the ground in a continuous process as long as heating is required.

Air source heat pumps are usually easier to install than ground source as they don’t need any trenches or drilling, but they can be less efficient than GSHPs. Water source heat pumps can be used to provide heating in homes near to rivers, streams and lakes.

Air Source Heat Pumps

Heat your home with energy absorbed from the air around you.

Air source heat pumps absorb heat from the outside air. This heat can then be used with mechanical ventilation units, under floor heating systems and hot water in your home.

An air source heat pump extracts heat from the outside air in the same way that a fridge extracts heat from its inside. It can get heat from the air even when the temperature is as low as -15 degrees celcius.

Air source heat pumps (also known as ASHPs) benefits include:
• could lower your fuel bills, especially if you are replacing conventional electric heating
• could provide you with an income through the government’s Renewable Heat Incentive (RHI)
• could lower your home’s carbon emissions, depending on which fuel you are replacing
• can heat your home and provide and hot water
• need little maintenance – they’re called ‘fit and forget’ technology
• can be easier to install than a ground source heat pump, though efficiencies may be lower.

Heat from the air is absorbed at low temperature into a fluid. This fluid then passes through a compressor where its temperature is increased, and transfers its higher temperature heat to the heating and hot water circuits of the house. There are two main types of air source heat pump system:
• An air-to-air system in Passivhaus buildings produces warm air to the mechanical ventilation system. With our "Green-Cube" they provide you with hot water as well.
• An air-to-water system distributes heat via your existing wet central heating system. Heat pumps work much more efficiently at a lower temperature than a standard boiler system would. So they are more suitable for under floor heating systems or larger radiators, which give out heat at lower temperatures over longer periods of time.

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Rainwater Recycling

Water butts collect rain from house or garage roofs, allowing gardeners to apply the water where it is needed most.

However, if space is available a rainwater harvesting system can be installed. A large tank is installed which is normally paved over. This collects water to use in gardens and in the house to flush toilets.

Rainwater harvesting (RWH) is the collection of rainwater directly from the surface(s) it falls on. This water would otherwise have gone directly into the drainage system or been lost through evaporation and transpiration. Once collected and stored it can be used for nonpotable purposes. These include toilet flushing, garden watering and clothes washing using a washing machine. You should note that were used for washing machines, if the quality of the collected water is poor, there can be issues with both colour and odour.

With a RWH system; the next step is to identify which type of system to install. There are a number of different systems available with a range of features. BS 8515 gives guidance on the design, installation and maintenance of RWH systems for the supply of non-potable water in the UK, and applies to both new build and retrofitting. The code of practice covers three basic types of RWH systems:
• water collected in storage tank(s) and pumped directly to points of use;
• water collected in storage tank(s) and fed by gravity to points of use; and
• water collected in storage tank(s), pumped to an elevated cistern and fed by gravity to the points of use.

Grey Water recycling

Wastewater from all sources in a property other than toilets is known as greywater.

Most greywater recycling systems collect and treat wastewater from showers, baths and wash basins, excluding the more contaminated water from washing machines, dish washing, kitchen sinks and dishwashers and comprises 50-80% of residential wastewater.

Greywater recycling systems collect this water, treat it and re-use it for purposes that do not require drinking water quality. This recycled water can be used to flush toilets, water gardens and sometimes feed washing machines.

There are two uses for grey water, either untreated for gardens, or with treatment this water can be re-used within the house for toilets or laundry. Systems are developing where the water can also be used within showers and baths.

Greywater reuse systems vary significantly in their complexity and size from small systems with very simple treatment to large systems with complex treatment processes. However, most have common features such as:
• a tank for storing the treated water;
• a pump;
• a distribution system for transporting the treated water to where it is needed; and
• some sort of treatment.

All systems that store greywater have to incorporate some level of treatment, as untreated greywater deteriorates rapidly in storage.

The main types of system are:
• Short retention systems
• Biological systems
• Bio-mechanical systems
• Integrated greywater/rainwater systems

Light fittings and appliances

The Passivhaus standard includes a target for unregulated energy demand which sets a primary energy limit of 120kWh/m2/yr. In order to achieve this, the primary energy demand for all activities (including cooking and appliances) within the home must be reduced. To achieve this, the specification of energy efficient light fittings and appliances needs to be carefully designed and considered.

Wherever possible an eco-system that incorporates low energy light fittings and bulbs should be used. It is also good practice to install low energy appliances.

When designing a passive house, the PHPP (Passivhaus Planning Package) software is used to calculate the electricity balance.

Step 1 is to calculate the electricity requirement in the house including all household appliances and lighting, refrigerators, freezers, cookers, artificial lighting, washing machines, tumble dryers, etc. with the highest energy efficiency available on the market should be used (i.e. category ‘A’ energy rating or better).

Step 2 is to calculate the auxiliary electricity requirement, in which electricity consumption is specified for mechanical ventilation system fans and controls, DHW circulation pumps, and any other present in the dwelling. The calculation results are presented in primary energy kWh/(m2a) and included in the PHPP ‘Verification page’.

Electricity Generation

In order to reduce the impact of electricity demand, electricity can also be produced on site, e.g. through PV, CHP (Combined Heat and Power, i.e. a generator that also produces heat, or a boiler, that produces electricity), wind power or micro hydro power.

Generate your own energy

Generating your own energy can be good for the environment and good for your pocket too. Low-carbon technologies such as solar panels, wind turbines, and wood fuel boilers use renewable sources of energy, so you use less fossil fuel, which reduces the carbon footprint as well as your fuel bills. There are also government financial incentives available.

None of the following are worthwhile unless you look at having the most energy efficient house, you can afford first, such as a Passivhaus, which looks at a fabric first approach prior to "bolting on" energy producing solutions.

Methods to produce electricity include:

Solar panels (PV)
Solar electricity systems, commonly known as solar photovoltaics (PV) capture the sun’s energy using photovoltaic cells. The cells convert the sunlight into electricity, which can be used to run household appliances and lighting.

Solar water heating
Solar water heating systems use free heat from the sun to warm domestic hot water, with a conventional boiler or immersion heater as backup, to make the water hotter or provide hot water when solar energy is unavailable.

Wind turbines
Wind turbines harness the power of the wind and use it to generate electricity. Small systems known as ‘microwind’ or ‘small-wind’ turbines can produce electricity to help power the lights and electrical appliances in a typical home.

Use running water to generate electricity, whether it’s a small stream or a larger river. Small or micro hydroelectricity systems can produce enough electricity for lighting and electrical appliances in an average home. Generates heat.

Wood-fuelled heating
Heat and hot water from wood-fuelled stoves and boilers. Wood-fuelled or biomass heating systems burn wood pellets, chips or logs to power central heating and hot water boilers or to provide warmth in a single room.