Category Archives: PHPP

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.

 

Design, Heat Recovery, Passive House Data, PHPP, Primary Heating, Research Tools, Software Tools, Software Tools, Tools and Aids

Heat Recovery Ventilation (HRV) Selection Part 2

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Selection of the HRV unit.

For those building to the Passive House standard the HRV is independently tested by the Passive House Institute. They provide a full list of certified units at the following link Passive House Certified Heat Recovery Units.   

HRV Efficiency (How is it calculated)

There are principally three methods it seems. One is the Supply method (used by manufactures) and this usually gives a higher efficiency value than the real world values. The Extract efficiency method is used to give a closer to real world value and then the passive house efficiency method which adds the following formulae to the Extract efficiency method.

Pel = real electrical power, W
M = mass flow, kg/h
Cp = specific heat of the air, kJ/kgK

The good news is that it appears if the HRV is certified to the Passive House standard then the difference between the supply method and the extract method  is very small.

In the near future I plan to connect to the HRV unit I purchased and view the efficiency values.

The Passive House certificate shows the following

HRV
HRV Calculation

 

Cost Efficiency

The most cost efficient unit I came across was the Airflow DV145 passive house certified unit for our 200 m2 house with an airflow capacity of 542 m3/h. I paid around €2200 for it. If one has a smaller floor area then more savings can be made by using a smaller unit. As a self builder technical support was important and their main offices are in the UK.

If one opts for a non-certified HRV unit a 12% reduction must be applied to the manufacturers specification . Some manufacturers might not renew the certificate each year so it is a good idea to ask if a certificate exists. The data must be entered in the planning software for the passive house. For those interested in the passive house planning software (PHPP)  there are courses run in Ireland frequently so I would suggest that one does this 3 day course (typical) and usually one finds the software discounted on the course.

It is an enjoyable course where one can select your own pace (the first time I did the course I wanted to listen and learn rather than calculate the performance of our own home). One such place is http://www.passivehouseacademy.com/

HRV Self BuildTo be continued………

 

Contact Details:      seamus.sheehy.selfbuild@gmail.com

Airtightness, Design, Heat Recovery, PHPP, Software Tools, Software Tools, Sound Proofing, Tools and Aids

Heat Recovery Ventilation (HRV) Selection- Part 1

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HRV OPTIONS

There are two types of HRV units that I came across -Heat (HRV) or Energy (ERV). The ERV is used principally for recovering humidity  and heat. I selected a HRV unit,

Size Matters

When selecting a HRV unit it appears that one of the biggest mistakes is to select a unit that is too small but still satisfies the current regulations. What appears to happen in the competitive world of quotations is that a unit that just ticks the box comes in as the best price.

In selecting a unit for our home I selected a unit that has a manufacturers capacity of 542m3/h where the floor area of our house is 205 m2. Currently the unit is running at 31% of its capacity and it is maintaining a CO2 (Carbon Dioxide) level of around 700 ppm when the four of us occupy it . I use a stand alone CO2 sensor to measure the CO2 in different rooms. (I have not commissioned the unit yet as the internal doors/glazing are not installed).  

Another advantage of selecting a larger unit is that it can run more efficiently at lower speeds and generates less noise through the ducts or from the unit itself.

Some of the options from the manufacturer Airflow (my unit is the third from the right).

HRV passive house
A choice from one particular manufacturer.

September 2018 performance (with no heating switched on yet).

The graph below gives an idea of how the HRV works when managing heat from the house and supplying fresh air. For the coldest days of the year so far (2 degrees at night-in September) I put the unit into summer bypass mode the next morning (take in outside air directly and pump it around the house) because the sun was shining that day. The winter sun is lower in the sky so solar gain increases in the winter (when the sun shines). The house is made of timber/glulam construction. The main thermal mass is the concrete floor at the moment soon to be covered by a 32 mm thick wooden floor so the response times of house I suspect will change. The floor and wall temperatures are approximately 22 degrees Celsius.

HRV Software review and Control.

Example above of HRV in use in our home.

Sample Data in our home using Google Fusion to visualise the HRV data for a week in October. (see link below)

  • One can select the chart tab and visualise the graph.
  • Use the bottom graph to zoom in.
  • The data is from the 21 October to the 28 October 2018.
  • One storage heater rated at 1.7kwh was used for 5.5 hours a day off peak.
  • The storage heater was switched off for one day on the 23rd October.
  • The graph starts at midnight on the 21 October.
  • Each ref reading is every 10 minutes.
  • The CO2 reading vary between 480ppm and 700ppm when fully occupied.

https://www.google.com/fusiontables/DataSource?docid=14U8eXcMzhritW7dQTPSuBEIYNhyDcayGJUlnuLyi

Filters

All HRV units contain a maintainable part called filters. They have a number of functions.

  • Clean the air being pumped into the house, and
  • Keep the internal components such as fans, ducts and HRV housing clean.

One typically finds one coarse filter and one fine filter on the air supply into the house and a coarse filter on the extract air from the house before the extract fan. The coarse filter is typically a G4 and the fine filter is a F7 (Pollen filter). I installed a 400mm x 400mm  G4 coarse filter at the duct inlet so that I could keep the main supply duct clean. It is a bit more effort to maintain this but it will hopefully minimise the maintenance of the duct.

To be continued………

 

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.

 

 

 

 

 

 

 

 

Design, Passive House Data, PHPP, Tools and Aids

Performance Standard -Setting the Standard

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The passive house software allows one to set your own performance standard by selecting how much energy (oil/gas/electricity) one wants to use to heat the building.

For example current Irish house builds that comply with today’s standard 2014 are estimated to use 100watts per m2 (subjective). The passive house standard if one goes for certification uses 10w per m2 (objective).

The real benefit for using the PHPP software is that the performance approach can be set by the home user. For example if I want to reduce my energy consumption to 1.5 litres of oil per m2 of the house size then I can set the software to a maximum of 15kwh per m2 for the year while maintaining a temperature of 20 degrees Celsius.

In a typical 3 bedroom house with an area of 100m2 the oil usage would be 150 litres a year.  With the PHPP performance software one can set the number of litres of oil (or gas etc) per year that your residential or commercial property will use to within a small margin of error. In other words you select the performance value of your build.

In summary the PHPP software takes into account your comfort and health (temperature and oxygen levels)  by removing high CO2 levels and VOCs and providing an even temperature throughout the house.

Design, PHPP

A Performance Standard

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The Performance Standard

A performance standard is objective (quantitative) . One calculates the energy performance using software called the Passive House Institute planning package (PHPP). It calculates the energy gains and losses. Energy values for example are calculated from the number of people in the house, the solar gain, appliances, all types of losses such as the diameter of copper pipes feeding the hot water taps etc. This tool allows one to create a design for a new build or a renovation where the energy use can be quantified and set by the occupant.

Other solutions for managing building energy usage are in the majority rating systems. A rating system is subjective (nobody knows for sure how efficient it is or how much energy will be used). In Ireland the system is called BER (Building Energy Rating). In England they have BREEAM.

The Irish rating system is weighted towards adding on features such as a porch, solar panels, a heat pump etc., in order to get a high BER rating and it is subjective. One BER assessor may deem it an C2 and another a C3.

The passive house approach primarily aims to reduce and measure your energy consumption and only then do you add features such as solar panels or other heating systems.

While the two approaches exist the BER one is mandatory. What this means is that you could build a house to an energy performance standard that uses the lowest amount of energy in the world and fail to get the current Irish required BER rating.

My interest is the performance approach (using the passive house energy balancing software called PHPP) to design and build the house. As the old/new saying goes “if you can measure it you can manage it“.