Tag Archives: Self-Build

Heat Pumps (Air to Air), Heat Recovery, Insulation, Passive House Data, Thermal Bridge

Using a Heat Pump (Air to Air) to heat a house-Part 2

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Other advantages of an Air to Air heat pump compared to air to water heat pumps is the ability to supply heating when it is required and quickly switch off the unit if there is solar gain in the winter (the sun has been known to shine in Ireland in the winter months). The air to water heat pump will have a slower response time through the concrete floor.

Installation-The installation of the internal and external unit needs careful design/planning. Both need to be considered at the same time. The factors to consider for the external (Inverter) unit is a location that is not subjected to high winds (higher winds will mean lower temperatures during the heating season and reduced efficiency), mounting the unit at least 100mm (I used 300mm) from the rear wall (restricting air increases the energy usage). There should be no air flow restrictions in front of the unit either. Mount the unit on a secure and flat surface (the external inverter requires a flat surface so that compressors are balanced to reduce vibration). Vibration leads to lower reliability. The length of the pipework also needs to be considered and noise levels. The maximum noise level for our unit is 61db if on full power.

The external unit requires an electrical isolation switch and a condensation drain for the cooling season (it removes moisture from inside the house).

Power Consumption-The maximum power consumption of the external unit is 1.6kw with a typical power consumption of 1.08kw to produce up to 4kw of internal heating. Typically a passive house requires 1kw of internal heating for each 100m2 on the coldest day of the year . Our home is 200m2 so 2kw is required. The 4kw output power will allow more heat capacity if required. Most Air to Air heat pumps have an option to control the output power using the remote control. One can reduce the power to 50% or 75% of its rating. I will set ours to 50% for year 2 (2024-2025) which approximately equates to a max heat output of 2Kw on the coldest day of the year. This has the advantage for passive house builds of increasing the life of the Heat Pump compressor and ensuring the unit does not use more power than is required. It will also reduce the noise level by 4db (which equates to a reduction of noise by approximately half).

Typical Operation-The operating temperature range of the external inverter is –15 degrees to +24 degrees in the heating cycle. The typical internal heating temperatures achieved for 6 degrees and 7 degrees outside temperatures are shown below. Most heat pumps will also have an automatic defrost cycle when the external unit freezes over due to low outside temperatures. No heat will be delivered inside the home during this cycle and it only lasts a short period of time. If a house is designed with the passive house software (PHPP software) it could take a day or two for the temperature to drop significantly due to the highest air tightness standard in the world (0.6 ACH), quality control around the building fabric and designed to a performance standard.

It is also important to mount the unit above ground level so that snow does not block the unit from functioning. A HO7RN-F (A rubber/Neoprene flexible cable) 4 core cable is required to connect the outside unit to the isolation switch (red switch shown below) which in turn requires another isolation switch inside that in turn controls both the inside and outside unit.

Cables and Ductwork-The cables and ductwork installation for a heat pump with a timber frame construction requires care during installation. When locating the cable and duct route through the wall use a narrow hollow pipe to find a path through the insulation and then drill through this pipe. If one uses a drill on its own with fibreglass insulation will wrap itself around the drill and leave thermal gaps in the wall and result in thermal bridges. The method I used is shown below. I used a rubber airtight gland to seal the larger duct. Ensure that this hole is mechanically sealed during the interim works from any rodents entering your build.

Power Usage-For year one of the installation I experimented with different settings -example using a high heating mode during off peak lower cost electricity and then returned to lower heat output during day. For year two I will set the unit at 50% of its output heating capacity and try an option called ECO mode which automatically reduces the temperature over time. For the last two weeks in this mode (October week 1 and 2) the unit used 20Kwh (€5 @ 0.25 cents per Kwh) to heat the house. The input power used by the air to air heat pump was approximately 300 watts when heat was required. The plan is to increase the number of solar PV panels to offset this 300 watts during daytime use. The power consumption varies as the external temperature changes. In the first year we used between 28Kwh per week up to a max of 50kwh during the first year of experimentation during the winter heating season. A power meter is now installed to record the daily/weekly and monthly power usage as shown below.

Below is the HRV (Heat Recovery Unit) temperature /humidity plot over the 2022-2023 winter period with the air to air heat pump. I reduced the HRV fan speed to minimise the amount of energy consumed in the winter time and increased it at the end of the winter season as shown below .

Internal Unit-The internal unit requires a height above floor level of 2.4 meters and at least 65mm clearance above the unit. In our installation there is approximately 1000mm clearance above the unit to allow the unit to blow air upwards to ensure a more balanced room temperature and air flow in the room. This is a built in function of this particular unit .

Further Experiments and Research-I am also experimenting with a secondary heat distribution unit to improve heat flow around the living area of the house in year 2 in order to optimise the temperature differences one finds at ceiling height versus floor temperature.

Heat Pumps (Air to Air), PHPP, Primary Heating, Thermal Bridge

Using a Heat Pump (Air to Air) to heat a house-Part 1

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Selection of a Low cost heating system for a passive house.

There are a number of options to heat a home when energy efficiency is designed into the build from day one. This statement is particularly true when one aims for the passive house performance standard using the PHPP (passive house planning package) software. When we moved into the house one will see from a previous blog that we started out with two storage heaters to heat the house with off-peak electricity with a capital cost of €70 (One storage heater was free and the other we paid €70 ).

Times have changed and the next energy crisis came along in 2022. We now have switched to a 1.6 kw air to air heat pump . These units are cheaper to run and more efficient than other types of heat pumps or heating systems. The other reason a dedicated home heating single unit was selected was to simplify maintenance. The hot water system is independent of the house heating.

One benefit of using an air to air heat pump to heat the house was the realisation that in Ireland when one returns home after being exposed to a damp cold climate it was difficult to thaw out quickly when the whole house temperature was 20/21 degree Celsius when using the storage heaters. By careful placement of the heat pump one room in the house is now at a higher temperature. This almost equates to a fireplace being available to help drive out the dampness one absorbed. We also noticed the room is used more frequently.

The room we selected was the kitchen/dining room. I feel it is important to ensure that the warm air the unit is blowing out does not interfere with the area one uses near or under the unit. This particular unit has an upward air circulation option that can limit this but we still installed it in an area that is not a functional working or sitting area.

To select the correct size of a heating source one needs to review the passive house PHPP software for your home. In principle the passive house standard selects the coldest day of the year for this calculation. In Ireland the PHPP software uses local climate data installed in the software to calculate the heating required for the house. This equates to approximately 1kw of heat for every 100m2 of floor area. As our home is 200m2 we needed 2 kw output on the coldest day of the year (similar to the power a toaster or hair-dryer uses for the coldest day).

The Air to Air heat pump we used was the RAS-B13J3KVSG-E internal unit and the RAS-13J2AVSG-E1. These were one of the most efficient and economical units I could find. The price of the unit was around €600. Installation was another €1000 approximately. There are designer internal heat pumps options available from the same brand if one want to make the unit a design feature.

How the heat pump works -All heat pumps harness the natural heat energy present in the environment, air-to-air heat pumps can amplify the input power, resulting in a higher output. This is known as the Coefficient of Performance (COP), which measures the ratio of output power to input power. A higher COP indicates greater efficiency, and air-to-air heat pumps typically have a COP of 3-4, meaning they can produce 3-4 units of energy for every unit of electricity consumed. The air to air heat we installed has a SCOP of 6.3 and the designed heating load for the year is 752kw/h per annum. This approximately equates to €25 a month for a 7 month heating season @23 cents a kw/h. The letters SCOP is a seasonal calculation for the full heating season. In our unit the COP can produce 20 degrees inside if the temperature is 7 degrees outside.

There is also a function to cool the house with an air to air heat pump when global warming arrives in Ireland. Ireland missed the global warming cycle this year (2024) so we did not need to use this function.

Part 2 -Installation, performance and lessons learnt after 1 year of use…to be continued…

Solar Hotwater, Solar PV, Tools and Aids

Solar PV for the self builder -Part 2b

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Analysing a Solar PV quotation.

PV Panel Options-Output wattage of pv panels are typically available in the range 270 Watt, 340 Watt, 375 Watt, 455 Watt. A manufacturer’s brand name will add to the price. Some brands names are LG, QCELL, LONGI, REC etc. A manufacturer warranty can be up to 25 years. A performance warranty of up to 25 years is available.

Example -A Qcell 340 W , 25 year manufacturer warranty and performance warranty can be purchased for €60 ex vat, a REC 365W for €165, a LG 440W for €261. Some manufacturers are now including a labour warranty of between 10 and 25 years.

Inverters Options-The standalone single inverter price varies from around €160 for a 1.5kw system and increases to approximately €1,300 for a 10kw inverter for the domestic market (single phase). The number of MPPT channels provided in the inverter changes the price-a single MPPT channel inverter will usually be cheaper than a dual MPPT channel inverter. MPPT methods also affect the price (a list of the mppt types available are listed here–for the techies.) As above the manufacturer brand name and the length of the manufacturers warranty also dictate the price you pay.

Hybrid Inverters (those that charge batteries) start at around €600 for a 3kw system and increase to €1600 for a 5kw system. The warranty varies from about 2 years to 25 years. When purchasing an inverter one must ensure that it has a certificate of compliance to match the national grid profile (a grid profile determines when the inverter should switch off and on if there was a power failure) . So purchasing a cheaper inverter online might not be compatible with the national standards required in each country. This grid profile is usually programmed/selected when installing the inverter.

Another option when purchasing a central inverter is to install optimizers . These provide as a means to improve the solar output if shading exists when using a central inverter. These cost around €50 each.

Microinverters prices start at around €100 for a 350 watt pv panel and increase to approximately €160. Warranty’s vary from 10 years to 25 years. Some brand names that exist are Enphase, TSUN , BPE. They require a single management control unit that controls, configures and allows one to monitor the performance remotely on a desktop or mobile phone App. The brand name also carries a cost. The microinverter is able to monitor the performance of each individual solar panel and inform you about an individual failure or issues. They also offer one of the best ways to manage shading from trees, chimneys, etc., or different orientations as stated earlier. This single control unit costs approximately €140 to €280 depending on the functions you require. These unit types generally have an AC charging function similar to the Tesla battery systems.

Part 3 to follow….

Building Physics, Design, Passive House Data, PHPP, Software Tools, Tools and Aids, Window/Door Installation, Windows

Self Build-Building a New Home-Self Builder

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Factory Built or Site Construction 

There are many options today when deciding to build. One can use a factory built design or use traditional block work or timber frame on site. Some factory built designs are as follows by way of example  http://www.scanhome.ie .  One can select the level of input oneself such as only construct the frame and say the self builder can do the rest or let the builder/supplier do everything.

How much Work does a self builder take on.

As a self builder I would try and get the foundation, frame, roof and windows installed then one can work in the dry to finish it. One is left with indoor wall completion, plastering , air tightness, Heat recovery, Wiring, Plumbing, Rain Water Harvesting, House heating System, Water heating system, floor finish, Painting, furniture , kitchen more than enough work for the self builder. The above need to be well thought out before laying the foundation or erecting the frame and the finish design of the roof.

The Building Standards-Self Build

One needs to comply with the building regulations. Always remember these are the minimum standard. It is always better to go for a home that will last well into the future that is warm and supplies fresh air.  A lot of new homes built today are of a poor standard and this can be seen in the UK and Ireland. See example https://energysaveguy.tumblr.com.

The Sales Pitch

There are buildings that can receive different rating systems such as  LEED and BREEAM.  A good video on the good, the bad and the ugly of these can be seen here.  They focus on equipment and energy accessories so it is best to leave these and focus on the basics. What are the basics –Insulation, Air-tightness, Windows, Heat Recovery (fresh air supply), and minimising thermal bridging (heat loss through details on the build).  When one does the above one finds that the heating system is simple, the house costs very little to run and is healthy if the correct materials are selected and installed in correct sequence during the build.

The Gold Standard-Passive House

The highest energy standard to build a house , an apartment, school or commercial buildings is the passive house standard. It focuses on the basics and uses physics rather than rating systems to design the building.  All the calculations are done before the house is built on a passive house planning software package (PHPP) which takes into account for example how much solar heat the glass in the window will leave into the house, how much heat will be lost through the glass from the inside to outside, how much heat is lost through the frame, and the heat lost on how the window is installed in the wall. Every building detail physics are analysised to ensure that one ends up with a comfortable home.

 

Airtightness, Building Physics, Design, Heat Recovery, Passive House Data, PHPP, Tools and Aids

Air tightness Test-Passive House 0.22ACH

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Self Build air tightness test -0.22ach with a volume of 603 m3 @ 50 pascals. 

When one is building to a performance standard the day of reckoning is the airtight test. The reason for this is that when one is pumping fresh air into the house using a Heat Recovery System, rather than relying on simple multiple holes in the wall, it becomes important to control where the fresh air is coming from and where the heat is going.

Airtight Test
Airtight Test

 

 

 

 

 

 

If air is leaking in or out around windows /doors/walls or other gaps in the building fabric then heat is lost and moisture problems in the form of mould can arise or else give rise to damage to the building fabric.

The pressure 50 pascals equates to a 20 mile per hour wind which is not too untypical in Ireland. So if one opts for the Irish  building standard (a minimum standard) this equates to the air in the house changing/leaking 7 times a hour when a wind blows at 20 miles per hour. No wonder people block up the hole in the wall vents .

  • The current Irish building standard  require 7 air changes  per hour (ach) also called leakage at 50 pascals  typically with no heat recovery system.  As a guidance heat recovery manufactures recommend 3 Air leakages per hour to ensure that the heat recovery system can push fresh air into the house and recover heat leaving the house through its own system rather than through gaps in the building fabric.
  • The passive house standard for a new house requires 0.6 Air changes per hour (ach) at 50 pascals to ensure the heat recovery system works efficiently, ensure that occupants receive the correct amount of fresh air and minimise building fabric damage.

The passive house test differs from the Irish test because it must include pressurisation and depressurisation and use the volume as set out per Vn50 (EN13829).

The Test

Gavin O Shea from Greenbuild was hired for the job.  He is certified/audited by the National Standards Authority of Ireland (NSAI).

The preparation for this entailed sealing all cable ducts and the inlet and outlet pipes for the Heat Recovery System. One also ensures that the shower and sink outlet traps are full of water. The overflow outlet for two water tanks were not sealed off. I did consider a duck valve but it was not in place at the time of the test.

Air Tight Test
Airtight Test

 

 

 

 

 

 

 

 

The test using the Irish method gave a result of 0.181 m3
/(hr.m2).

Gavin O Shea calculated that the equivalent size hole that equates to a result of 0.22 ach is approximately 65.25 cm2 (@50Pa) or a hole 81mm x 81mm if all of the leaks present in the dwelling were concentrated into one hole. That is about a tenth of an A4 sheet of paper.

The results of the air tight test can also help determine the selection of the  Heat Recovery System. If the airtight test is lower then more options are available when selecting a unit.

From my research a passive house standard Heat Recovery Unit will cost more because it needs to be independently tested by the Passive House Institute using their test method. Heat Recovery manufactures have also the burden of putting the unit through national tests or international tests with the end result being the customer pays more.  One has also the option to select a non passive house certified unit for a passive house but when calculating the performance value one needs to account for this in the PHPP software with a 12% reduction below the manufacturers performance claim.

If one wants to view certified Heat Recovery Units one can find and sort them at the following link.  One can see for example at this link the capacity (Column- Air Flow Range) that these units have as it is important to select a unit that is oversized for your particular self build. I would compare it to selecting a mini car to tow a caravan up a hill compared to using a larger car. The small car will struggle from an efficiency and noise point of view while the larger car will be quieter and more efficient at the require flow rates.  I will do a separate post on how I selected our Heat Recovery Unit.

 

 

 

 

 

 

 

 

Painting, Partitions, Plasterboard, Tools and Aids, Walls

Painting

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Research

Having carried out some DIY painting in the past I decided this time I would invest in good tools as this was going to be the biggest job to date. This first entailed selecting a brand whose painting equipment is rated highly.  I selected tools from the Wooster product range.

There are a few essential tools.
    • The Pole (I selected a 4 to 8 foot adjustable pole called the Wooster Sherlock GT extension pole ). This tool has a few good features such as snap on paint roller head, an extension that snaps in set positions, a tool to fit screw type paint rollers. A substantial rubber hand grip that made the job easier . The highest point of our ceilings are 3.6 metres and this version allowed me to reach the ceilings directly from the floor. Narrow hallways that are less than the length of the pole plus the roller would make it difficult to use this pole length.

 

 

 

 

 

 

 

 

 

 

  • Rollers– I selected a 3/8 inch nap (pile depth)  for the plasterboard because of its smooth surface and I tried a 9 and 14 inch roller called the pro-doo-z. The Nap determines the amount of paint applied and the paint texture of the wall surface . The 3/8 inch gives a fine finish. If one used a 1/2 inch nap the roller can hold more paint but the texture is different. After trying the 9 inch and 14 inch roller my preference was to use the 14 inch roller as I found it easier, faster and more stable because it is supported at both ends (see below). I would be tempted to try the contract rollers that are supposed to be faster the next time but the finish may not be the same. One can select the right roller from the web site link Wooster Rollers. 
        • Cutting In– A very useful and time saving tool was the Wooster hand-held Pelican kettle .

          Pelican Kettle

          It is available with liners to make it easy to change colours.  It has a section to hold a cutting in brush and a mechanism to hold a small roller. Both of these are necessary in order to end up with the same wall surface texture as the main roller for example around switches and sockets. I used non diluted paint for the cutting in process. One needs a mini roller also for the Pelican holder.

        • Brush– The cutting in brush I used was the Silver tip wooster 2 inch model. I never owned a high quality brush before and it is working out great.
        • Tray/Kettle-I tried the Tray and the Kettle. My preference is the 25 litre Kettle with replaceable liners. I initially bought a Kettle with no liners and the washing out of the tray or kettle at the end of a days painting is time consuming and  non environmental as one must wash the inside completely . Comparing this to using a liner that one can dispose of in the bin. I know at the end of the day it all is non environmental but using plastic liners keeps everything clean and saves time.
        • Safety Glasses and peaked cap -While painting the ceiling it is a vital item.
        • Fresh Air– While the paint is wet the smell is stronger so ensure that your rooms are very well vented. As I am painting in the winter the house temperature has dropped to approximately 9 degrees.
        • Paint-I used Dulux paint as it has a good reputation for quality.
        • Cling Film-In order to keep the brushes and rollers clean I wrapped them in clingfilm overnight. The roller lasted a week and I did not notice any problems even with this amount of time . One just took of the clingfilm and started again with no cleaning required. It also reduces waste.

Technique I used for painting

First Coat– For the first coat on the plasterboard I mixed the paint to a 3 to 1 ratio  (one litre of water to 3 litres of paint) as advised.  By diluting the paint for the first coat it is supposed to allow the paint to get a good bond with the paper finish on the plasterboard. I did not use the traditional wet plaster method on the walls. The paint also needs to be mixed in a separate container. One requires a 1 litre container to carry out the measuring. I experimented with a lower ratio of water and I could not see much of a difference with the Dulux matt white paint on the bare plasterboard only that with two paint coats undiluted the finish looked better . If the walls were wet plastered in the traditional way then the water mix appears to be vital.

I started out using the paint brush and mini roller for the first cutting in but later on I just used the paint brush for the first cut and then used the paint brush and mini roller for the second cut in order to finish with the same texture as the 14 inch roller.

Self Build Painting
14 Inch Roller

After watching numerous methods and comparing the comments I think the following is the best I have come across to date  and having used the ideas it it all makes sense. With Youtube I found one has to watch about ten videos and then decide who is doing it right. Below may help.

https://youtu.be/v61PVzLNemk

Imperfections .

When the first coat of paint is applied it often identifies small imperfections in the plastering. When this happens let the paint dry and fill the imperfection with USG or Gyproc ready made joint filler. When this has fully dried sand it by hand and repaint it with a few coats. This method worked for me.

 

Foundation

Geopathic Stress Lines and other Energies

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Before the foundation began we had the geopathic stress lines on the plot checked out and any other energies that were on the land in its use over the centuries.

With this information the geopathic stress lines were identified in one future bedroom. The bed was moved to combat this and the other energies cleared.

My understanding is that the geopathic stress lines are like naturally occurring magnetic fields that run under the ground and for this reason we felt it was easy to minimise the risk by knowing about them if they existed on the plot and dealing with them at this stage of the self build.

For example some say there is no evidence that pylons and mobile phone masts can damage your health but we decided not to take a risk by building on another one of these issues known as geopathic stress lines. We are also addressing potential risks from other energies such as mains electricity, wi-fi etc. For example one person may be susceptible to hay-fever, a particular food allergy, mobile phones etc and another not.

Like all these things there is no way to be sure how one might be affected.  I think some people are more susceptible and we will try and design these potential risks out of the self build for this generation and the next generation who chose to live in the house.