Estimating the impact of crops on peak loads of a Building-Integrated Agriculture space

Figures & data

Fig. 1. Crop energy balance.

Table 1. Details of the fluxes formulated in the developed crop models.

	Benis, Reinhart, and Ferrão (2017)	Graamans et al. (2017)	Kokogiannakis and Cooper (2015)	Ward et al. (2015)
${q\mathrm{″}}_{\mathit{sol}}$	Experimental Value	–	f (${q\mathrm{\text{'}}\mathrm{\text{'}}}_{\mathit{sol}\_tr,}{\rho }_r$)	f (${q\mathrm{\text{'}}\mathrm{\text{'}}}_{\mathit{sol}},$ LAI, $I_{\mathit{electric}},$$\mathrm{ }{k}_l$) De Zwart (1996)
${q\mathrm{″}}_{SW}$	–	f ($I_{\mathit{electric}},$$\mathrm{ }{\rho }_r,$$\mathit{CAC}$)	–	f (LAI, $I_{\mathit{electric}},$$\mathrm{ }{k}_l$)
${q\mathrm{″}}_{\mathit{LWX}}$	–	–	–	f ($T_{pl},$$\mathrm{ }{T}_{\mathit{sky}}$)
$q_{st}^{\text{″}}$	–	–	✓	✓
$q_{\mathit{morph}}^{\text{″}}$	–	–	–	–
$q_{\mathit{conv}}^{\text{″}}$	–	f (LAI,$T_{pl},$ $T_{\mathit{amb}},$$\mathrm{ }{r}_a$)	f ($h_{\mathit{conv}},$ $T_{pl},$ $\mathit{vpd}$)	f ($T_{pl},$LAI, $T_{\mathit{amb}},$ $U_{\mathrm{\infty }}$)
$q_{\mathit{latent}}^{\text{″}}$	f (${q\mathrm{\text{'}}\mathrm{\text{'}}}_{\mathit{sol}},r_s,$ $r_a,$ VPD, LAI)	f ($\mathrm{ }{r}_s,$$\mathrm{ }{r}_a,$ VPD, LAI)	f (${q\mathrm{″}}_{\mathit{sol}},$$\mathrm{ }{r}_{st},$$\mathrm{ }{r}_a,$$\mathit{VPD}$)	f ($r_a,r_s,$ LAI, VPD)
	Stanghellini (1987)		Monteith (1965)
where :
$r_s$	f (LAI)	f (${q\mathrm{″}}_{SW}$)	f (${q\mathrm{″}}_{\mathit{sol}},$ $T_{\mathit{amb}},$ VPD)	f (VPD,$\mathrm{ }\left[{CO}_2\right],$${q\mathrm{″}}_{\mathit{sol}},$$T_{pl}$)
	Pamungkas, Hatou, and Morimoto (2014)	derived from Wang et al. (2016)	derived from Jarvis (1976)	Stanghellini (1987)
$r_a$	f ($U_{\mathrm{\infty }}$) Pamungkas, Hatou, and Morimoto (2014)	f ($U_{\mathrm{\infty }},$ $\mathit{LAI}$) Fuchs (1993)	f ($U_{\mathrm{\infty }}$) Thom and Oliver (1977)	f ($Le,Nu,d$) –

Fig. 2. Overview of the modeling approach.

Fig. 3. Configuration of the case study: (a) building and (b) BIA space.

Table 2. Building envelope characteristics.

Building envelope	Overall U-value, W/m^2·K
Roof	0.184
Walls	1.124
Floor	5.556
Fenestration	5.556, SHGC of 0.894

Table 3. Details of the fluxes formulated in the Graamans et al. (2017) lettuce model.

Graamans et al. (2017) term	HB equation term	Additional information
Net radiation ($R_{\mathit{net}}$)	${q\mathrm{\text{'}}\mathrm{\text{'}}}_{SW}=\left(1-{\rho }_r\right)·\mathit{CAC}·I_{\mathit{electric}}$	$I_{\mathit{electric}}$ is the PAR emitted by the horticultural electric lighting, W/m^2cultivated ${\rho }_r$ is the leaf reflection coefficient,% $\mathit{CAC}$ is the cultivated cover area, % ${\rho }_a$ is the air density, kg/m^3 $c_p$ is the specific heat of air, J/kg·K ${\chi }_s$ is the vapor concentration of the air, g/m^3 ${\chi }_a$ is the vapor concentration at the leaves, g/m^3 $\lambda$ is the latent heat of vaporization of water, J/g $r_s=60·\frac{1500+\mathit{PPFD}}{200+\mathit{PPFD}}$ is the stomatal resistance, s/m $r_a=100$ is the aerodynamic resistance, s/m
Sensible heat exchange ($H$)	${q^{,,}}_{\mathit{conv}}=\mathit{LAI}·{\rho }_a{c}_p\frac{T_{pl}-T_{\mathit{amb}}}{r_a}$
Latent heat exchange ($\mathrm{\lambda }\mathrm{E})$	${q^{,,}}_{\mathit{latent}}=\mathit{LAI}·\lambda \frac{{\chi }_s-{\chi }_a}{r_s+r_a}$

Table 4. Assumptions used to estimate the BIA space peak loads.

Load type	Crops are considered to estimate peak loads	Crops parameters		Electric lighting
		Activity	LAI
Sensible heating	Yes	Respiration	2.1/10	Off
Sensible cooling	No	–	0	On
Latent cooling	Yes	Photosynthesis	2.1/10	On

Table 5. Parametric study parameters.

Parameter	Range	Increment
Temperature, °C	19–24	1
Relative humidity, %	70–78	2
Cultivated density (CD), %	60–720	20
LAI	0, 2.1 or 10	N/A

Table 6. Reference vapor pressure deficit (VPD) (kPa) for leafy greens production in the BIA space¹.

Temperature, °C	Relative humidity, %
	70	72	74	76	78	80
19	0.66	0.62	0.57	0.53	0.48	0.44
20	0.70	0.66	0.61	0.56	0.52	0.47
21	0.75	0.70	0.65	0.60	0.55	0.50
22	0.79	0.74	0.69	0.64	0.58	0.53
23	0.84	0.79	0.73	0.68	0.62	0.56
24	0.90	0.84	0.78	0.72	0.66	0.60

¹ White cells represent values within the recommended VPD range of 0.65 kPa to 0.9 kPa, whereas shaded cells are values outside this range.

Table 7. Estimated rates of heat gain/loss induced by the crops (lettuces) for different activities and LAI for a ventilation rate of 0.02 h⁻¹.

BIA space conditions TDB, °C / RH, % (VPD)	Respiration				Photosynthesis^a
	Sensible Heat, W/m^2cultivated		Latent Heat, W/m^2cultivated		Sensible Heat, W/m^2cultivated		Latent Heat, W/m^2cultivated
	LAI 2.1	LAI 10	LAI 2.1	LAI 10	LAI 2.1	LAI 10	LAI 2.1	LAI 10
19/70 (0.66)	−37	−177	37	177	−14	−241	81	322
20/70 (0.70)	−39	−186	39	186	−17	−241	85	339
20/72 (0.66)	−36	−172	36	172	−13	−231	80	309
21/70 (0.75)	−41	−194	41	194	−21	−241	88	355
21/72 (0.70)	−38	−179	38	179	−16	−241	83	319
21/74 (0.65)	−34	−164	34	164	−11	−216	78	295
22/70 (0.79)	−42	−201	42	201	−24	−241	91	371
22/72 (0.74)	−39	−186	39	186	−19	−241	86	332
22/74 (0.69)	−36	−170	36	170	−14	−224	81	303
23/70 (0.84)	−44	−208	44	208	−27	−241	95	386
23/72 (0.79)	−40	−192	40	192	−22	−241	89	344
23/74 (0.73)	−37	−176	37	176	−17	−230	84	309
23/76 (0.68)	−34	−160	34	160	−12	−204	79	283
24/70 (0.90)	−45	−214	45	214	−30	−241	97	400
24/72 (0.84)	−41	−197	41	197	−25	−241	92	354
24/74 (0.78)	−38	−181	38	181	−20	−235	87	314
24/76 (0.72)	−34	−164	34	164	−15	−208	82	287
24/78 (0.66)	−31	−148	31	148	−10	−183	77	262

^a Under electric lighting of 168 W⋅m⁻²_cultivated/437 μmol⋅s⁻¹⋅m⁻²_cultivated

Fig. 4. BIA space heating design day sensible and latent loads profiles at a CD of 600%, VPD of 0.75 kPa and ventilation rate of 0.02 h⁻¹.

Fig. 5. BIA space cooling design day sensible and latent loads profiles at a CD of 600%, VPD of 0.75 kPa and ventilation rate of 0.02 h⁻¹.

Fig. 6. Variation of the BIA space peak sensible heating load with the cultivated density for a ventilation rate of 0.02 h⁻¹.

Fig. 7. Variation of the BIA space sensible and latent cooling peak loads with the cultivated density for a ventilation rate of 0.02 h⁻¹.

Benis, K., C. Reinhart, and P. Ferrão. 2017. Development of a simulation-based decision support workflow for the implementation of Building-Integrated Agriculture (BIA) in urban contexts. Journal of Cleaner Production 147:589–602. doi:10.1016/j.jclepro.2017.01.130

 Web of Science ®Google Scholar

Graamans, L., A. van den Dobbelsteen, E. Meinen, and C. Stanghellini. 2017. Plant factories; crop transpiration and energy balance. Agricultural Systems 153:138–47. doi:10.1016/j.agsy.2017.01.003

 Web of Science ®Google Scholar

Kokogiannakis, G., and P. Cooper. 2015. Evaluating the environmental performance of indoor plants in buildings. Proceedings of the 14th International Conference of IBPSA - Building Simulation, Hyderabad, India, December 7–9.

 Google Scholar

Ward, R., R. Choudhary, C. Cundy, G. Johnson, and A. McRobie. 2015. Simulation of plants in buildings; incorporating plant-air interactions in building energy simulation. Proceedings of the 14th Conference of International Building Performance Simulation Association, Hyderabad, India, December 7–9.

 Google Scholar

De Zwart, H. F. 1996. Analyzing energy-saving potentials in greenhouse cultivation using a simulation model. Ph. D. Thesis, Wageningen Agricultural University, Wageningen.

 Google Scholar

Monteith, J. L. 1965. Evaporation and environment: The state of the movement of water in living organisms. Symposia of the Society for Experimental Biology 19:205–34.

 PubMedGoogle Scholar

Pamungkas, A. P., K. Hatou, and T. Morimoto. 2014. Evapotranspiration model analysis of crop water use in plant factory system. Environmental Control in Biology 52 (3):183–8. doi:10.2525/ecb.52.183

 Google Scholar

Wang, J., W. Lu, Y. Tong, and Q. Yang. 2016. Leaf morphology, photosynthetic performance, chlorophyll fluorescence, stomatal development of lettuce (Lactuca sativa L.) exposed to different ratios of red light to blue light. Frontiers in Plant Science 7:250. doi:10.3389/fpls.2016.00250

 PubMed Web of Science ®Google Scholar

Jarvis, P. 1976. The interpretation of the variations in leaf water potential and stomatal conductance found in canopies in the field. Philosophical Transactions of the Royal Society of London B: Biological Sciences 273 (927):593–610.

 Web of Science ®Google Scholar

Fuchs, M. 1993. Transpiration and foliage temperature in a greenhouse. Proceedings of International Workshop on Cooling Systems for Greenhouses, Tel Aviv, Israel.

 Google Scholar

Thom, A., and H. Oliver. 1977. On Penman's equation for estimating regional evaporation. Quarterly Journal of the Royal Meteorological Society 103 (436):345–57. doi:10.1002/qj.49710343610

 Web of Science ®Google Scholar