[esp-r] Re: Adding HRV to model - exemplar showing different approaches.

[Jon Hand]

In a recent development_branch update is a new ESP-r model which explores
several different ways of representing MVHR - from the 'reduce infiltration'
approach to a plant systems approach via representing the exchanger as
a collection of zones with hc coefficients and mass flow network.  Look
in the folder training/mvhr_representations/cfg/mvhr_testsa.cfg

Note: this exemplar does not include the two dummy zone approach
mentioned in Paul Strachan's email.

-Jon Hand
________________________________________
From: esp-r-bounces at lists.strath.ac.uk [esp-r-bounces at lists.strath.ac.uk] on behalf of Paul Strachan [paul at esru.strath.ac.uk]
Sent: 05 December 2013 21:26
To: Alex Giroux; esp-r at lists.strath.ac.uk
Subject: [esp-r] Re: Adding HRV to model

Alex,

We had a similar problem when we wanted to have a simple efficiency factor for the HRV, but wanted to have the correct outside CO2 concentration (outside RH in your case) for the supply air.

An effective solution was to have two "dummy zones". Suppose the efficiency of your HRV is 80%. Then set up the model so that 80% of the extract from the house goes into dummy zone 1, plus 20% outside air. This means that the temperature of dummy zone 1 will be correct as a supply temperature.

Then set up dummy zone 2 with outside air going in and the extract from this zone supplying the house at the 100% level. Set up a control so that the temperature of this dummy zone 2 is equal to the temperature of dummy zone 1.

Regards
Paul

________________________________
From: esp-r-bounces at lists.strath.ac.uk [esp-r-bounces at lists.strath.ac.uk] on behalf of Alex Giroux [asgiroux at uwaterloo.ca]
Sent: 05 December 2013 18:27
To: Jeremy Cockroft
Cc: esp-r
Subject: [esp-r] Re: Adding HRV to model

Thanks for the reply. Unfortunately, simply reducing the air flow isn't going to work. We're looking at both sensible and latent loads within the zone, and reducing the airflow will also reduce the amount of moisture brought in from the outside.

I need to find a way to precondition my ventilation air without affecting the amount of moisture being brought into the zone. Right now I'm trying to see if I can set up a second zone in my model as the "plant" - the plant zone will bring in exterior supply air at a given flow rate, heat it, and then the main zone will draw all it's ventilation air directly from the plant zone. If I'm understanding this correctly, I can set up the control loop in the plant zone to provide sensible control only, so the air entering the main zone will have the same humidity ratio as the exterior air.

Is this something that anyone has done before? Is there any other way to set up an HRV in ESP-r without explicitly modelling all the heating and cooling equipment within a zone?

Thanks.


On 3 December 2013 10:09, Jeremy Cockroft <jeremy at esru.strath.ac.uk<mailto:jeremy at esru.strath.ac.uk>> wrote:
Alex, keep it simple, as in this example:
If your HRV is 80% efficient, and handles, say 100m3/h, then set your ventilation rate at 20m3/h (as this is all that you require to heat, the balance being recovered by the HRV).  You may have infiltration as well, as in your base case, to include.  This avoids all that pesky plant simulation.
Regards,
Jeremy Cockroft

From: esp-r-bounces at lists.strath.ac.uk<mailto:esp-r-bounces at lists.strath.ac.uk> [mailto:esp-r-bounces at lists.strath.ac.uk<mailto:esp-r-bounces at lists.strath.ac.uk>] On Behalf Of Alex Giroux
Sent: 03 December 2013 14:18
To: esp-r
Subject: [esp-r] Adding HRV to model

Hi,
I'm looking for information on how to simulate HRVs in ESP-r.

I've got a house modelled, and I've run simulations to see what the loads are. I'd like to see how adding an HRV affects the loads on the house.
I can't find any specific information about how to go about doing this though. Can I add in an HRV somehow to a model with an idealized plant, similar to the hybrid mechanical/natural ventilation example in ESP-r? That example has the plants to provide mechanical ventilation to the zones set up as separate zones and then I believe there's an airflow network set up between the different zones, but I think I'm missing some files.
Thanks in advance.

Alex Giroux

--
Alexandra Giroux, EIT
MASc Student
Mechanical Engineering
University of Waterloo

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